docs: move ia64 architecture docs under Documentation/arch/

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.  Move
Documentation/ia64 into arch/ and fix all in-tree references.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

11 files changed, 2275 insertions, 1 deletions

diff --git a/Documentation/arch/ia64/aliasing.rst b/Documentation/arch/ia64/aliasing.rst
new file mode 100644
index 00000000000000..36a1e1d4842b81
--- /dev/null
+++ b/Documentation/arch/ia64/aliasing.rst
@@ -0,0 +1,246 @@
+==================================
+Memory Attribute Aliasing on IA-64
+==================================
+
+Bjorn Helgaas <bjorn.helgaas@hp.com>
+
+May 4, 2006
+
+
+Memory Attributes
+=================
+
+    Itanium supports several attributes for virtual memory references.
+    The attribute is part of the virtual translation, i.e., it is
+    contained in the TLB entry.  The ones of most interest to the Linux
+    kernel are:
+
+	==		======================
+        WB		Write-back (cacheable)
+	UC		Uncacheable
+	WC		Write-coalescing
+	==		======================
+
+    System memory typically uses the WB attribute.  The UC attribute is
+    used for memory-mapped I/O devices.  The WC attribute is uncacheable
+    like UC is, but writes may be delayed and combined to increase
+    performance for things like frame buffers.
+
+    The Itanium architecture requires that we avoid accessing the same
+    page with both a cacheable mapping and an uncacheable mapping[1].
+
+    The design of the chipset determines which attributes are supported
+    on which regions of the address space.  For example, some chipsets
+    support either WB or UC access to main memory, while others support
+    only WB access.
+
+Memory Map
+==========
+
+    Platform firmware describes the physical memory map and the
+    supported attributes for each region.  At boot-time, the kernel uses
+    the EFI GetMemoryMap() interface.  ACPI can also describe memory
+    devices and the attributes they support, but Linux/ia64 currently
+    doesn't use this information.
+
+    The kernel uses the efi_memmap table returned from GetMemoryMap() to
+    learn the attributes supported by each region of physical address
+    space.  Unfortunately, this table does not completely describe the
+    address space because some machines omit some or all of the MMIO
+    regions from the map.
+
+    The kernel maintains another table, kern_memmap, which describes the
+    memory Linux is actually using and the attribute for each region.
+    This contains only system memory; it does not contain MMIO space.
+
+    The kern_memmap table typically contains only a subset of the system
+    memory described by the efi_memmap.  Linux/ia64 can't use all memory
+    in the system because of constraints imposed by the identity mapping
+    scheme.
+
+    The efi_memmap table is preserved unmodified because the original
+    boot-time information is required for kexec.
+
+Kernel Identity Mappings
+========================
+
+    Linux/ia64 identity mappings are done with large pages, currently
+    either 16MB or 64MB, referred to as "granules."  Cacheable mappings
+    are speculative[2], so the processor can read any location in the
+    page at any time, independent of the programmer's intentions.  This
+    means that to avoid attribute aliasing, Linux can create a cacheable
+    identity mapping only when the entire granule supports cacheable
+    access.
+
+    Therefore, kern_memmap contains only full granule-sized regions that
+    can referenced safely by an identity mapping.
+
+    Uncacheable mappings are not speculative, so the processor will
+    generate UC accesses only to locations explicitly referenced by
+    software.  This allows UC identity mappings to cover granules that
+    are only partially populated, or populated with a combination of UC
+    and WB regions.
+
+User Mappings
+=============
+
+    User mappings are typically done with 16K or 64K pages.  The smaller
+    page size allows more flexibility because only 16K or 64K has to be
+    homogeneous with respect to memory attributes.
+
+Potential Attribute Aliasing Cases
+==================================
+
+    There are several ways the kernel creates new mappings:
+
+mmap of /dev/mem
+----------------
+
+	This uses remap_pfn_range(), which creates user mappings.  These
+	mappings may be either WB or UC.  If the region being mapped
+	happens to be in kern_memmap, meaning that it may also be mapped
+	by a kernel identity mapping, the user mapping must use the same
+	attribute as the kernel mapping.
+
+	If the region is not in kern_memmap, the user mapping should use
+	an attribute reported as being supported in the EFI memory map.
+
+	Since the EFI memory map does not describe MMIO on some
+	machines, this should use an uncacheable mapping as a fallback.
+
+mmap of /sys/class/pci_bus/.../legacy_mem
+-----------------------------------------
+
+	This is very similar to mmap of /dev/mem, except that legacy_mem
+	only allows mmap of the one megabyte "legacy MMIO" area for a
+	specific PCI bus.  Typically this is the first megabyte of
+	physical address space, but it may be different on machines with
+	several VGA devices.
+
+	"X" uses this to access VGA frame buffers.  Using legacy_mem
+	rather than /dev/mem allows multiple instances of X to talk to
+	different VGA cards.
+
+	The /dev/mem mmap constraints apply.
+
+mmap of /proc/bus/pci/.../??.?
+------------------------------
+
+	This is an MMIO mmap of PCI functions, which additionally may or
+	may not be requested as using the WC attribute.
+
+	If WC is requested, and the region in kern_memmap is either WC
+	or UC, and the EFI memory map designates the region as WC, then
+	the WC mapping is allowed.
+
+	Otherwise, the user mapping must use the same attribute as the
+	kernel mapping.
+
+read/write of /dev/mem
+----------------------
+
+	This uses copy_from_user(), which implicitly uses a kernel
+	identity mapping.  This is obviously safe for things in
+	kern_memmap.
+
+	There may be corner cases of things that are not in kern_memmap,
+	but could be accessed this way.  For example, registers in MMIO
+	space are not in kern_memmap, but could be accessed with a UC
+	mapping.  This would not cause attribute aliasing.  But
+	registers typically can be accessed only with four-byte or
+	eight-byte accesses, and the copy_from_user() path doesn't allow
+	any control over the access size, so this would be dangerous.
+
+ioremap()
+---------
+
+	This returns a mapping for use inside the kernel.
+
+	If the region is in kern_memmap, we should use the attribute
+	specified there.
+
+	If the EFI memory map reports that the entire granule supports
+	WB, we should use that (granules that are partially reserved
+	or occupied by firmware do not appear in kern_memmap).
+
+	If the granule contains non-WB memory, but we can cover the
+	region safely with kernel page table mappings, we can use
+	ioremap_page_range() as most other architectures do.
+
+	Failing all of the above, we have to fall back to a UC mapping.
+
+Past Problem Cases
+==================
+
+mmap of various MMIO regions from /dev/mem by "X" on Intel platforms
+--------------------------------------------------------------------
+
+      The EFI memory map may not report these MMIO regions.
+
+      These must be allowed so that X will work.  This means that
+      when the EFI memory map is incomplete, every /dev/mem mmap must
+      succeed.  It may create either WB or UC user mappings, depending
+      on whether the region is in kern_memmap or the EFI memory map.
+
+mmap of 0x0-0x9FFFF /dev/mem by "hwinfo" on HP sx1000 with VGA enabled
+----------------------------------------------------------------------
+
+      The EFI memory map reports the following attributes:
+
+        =============== ======= ==================
+        0x00000-0x9FFFF WB only
+        0xA0000-0xBFFFF UC only (VGA frame buffer)
+        0xC0000-0xFFFFF WB only
+        =============== ======= ==================
+
+      This mmap is done with user pages, not kernel identity mappings,
+      so it is safe to use WB mappings.
+
+      The kernel VGA driver may ioremap the VGA frame buffer at 0xA0000,
+      which uses a granule-sized UC mapping.  This granule will cover some
+      WB-only memory, but since UC is non-speculative, the processor will
+      never generate an uncacheable reference to the WB-only areas unless
+      the driver explicitly touches them.
+
+mmap of 0x0-0xFFFFF legacy_mem by "X"
+-------------------------------------
+
+      If the EFI memory map reports that the entire range supports the
+      same attributes, we can allow the mmap (and we will prefer WB if
+      supported, as is the case with HP sx[12]000 machines with VGA
+      disabled).
+
+      If EFI reports the range as partly WB and partly UC (as on sx[12]000
+      machines with VGA enabled), we must fail the mmap because there's no
+      safe attribute to use.
+
+      If EFI reports some of the range but not all (as on Intel firmware
+      that doesn't report the VGA frame buffer at all), we should fail the
+      mmap and force the user to map just the specific region of interest.
+
+mmap of 0xA0000-0xBFFFF legacy_mem by "X" on HP sx1000 with VGA disabled
+------------------------------------------------------------------------
+
+      The EFI memory map reports the following attributes::
+
+        0x00000-0xFFFFF WB only (no VGA MMIO hole)
+
+      This is a special case of the previous case, and the mmap should
+      fail for the same reason as above.
+
+read of /sys/devices/.../rom
+----------------------------
+
+      For VGA devices, this may cause an ioremap() of 0xC0000.  This
+      used to be done with a UC mapping, because the VGA frame buffer
+      at 0xA0000 prevents use of a WB granule.  The UC mapping causes
+      an MCA on HP sx[12]000 chipsets.
+
+      We should use WB page table mappings to avoid covering the VGA
+      frame buffer.
+
+Notes
+=====
+
+    [1] SDM rev 2.2, vol 2, sec 4.4.1.
+    [2] SDM rev 2.2, vol 2, sec 4.4.6.
diff --git a/Documentation/arch/ia64/efirtc.rst b/Documentation/arch/ia64/efirtc.rst
new file mode 100644
index 00000000000000..fd832840830152
--- /dev/null
+++ b/Documentation/arch/ia64/efirtc.rst
@@ -0,0 +1,144 @@
+==========================
+EFI Real Time Clock driver
+==========================
+
+S. Eranian <eranian@hpl.hp.com>
+
+March 2000
+
+1. Introduction
+===============
+
+This document describes the efirtc.c driver has provided for
+the IA-64 platform.
+
+The purpose of this driver is to supply an API for kernel and user applications
+to get access to the Time Service offered by EFI version 0.92.
+
+EFI provides 4 calls one can make once the OS is booted: GetTime(),
+SetTime(), GetWakeupTime(), SetWakeupTime() which are all supported by this
+driver. We describe those calls as well the design of the driver in the
+following sections.
+
+2. Design Decisions
+===================
+
+The original ideas was to provide a very simple driver to get access to,
+at first, the time of day service. This is required in order to access, in a
+portable way, the CMOS clock. A program like /sbin/hwclock uses such a clock
+to initialize the system view of the time during boot.
+
+Because we wanted to minimize the impact on existing user-level apps using
+the CMOS clock, we decided to expose an API that was very similar to the one
+used today with the legacy RTC driver (driver/char/rtc.c). However, because
+EFI provides a simpler services, not all ioctl() are available. Also
+new ioctl()s have been introduced for things that EFI provides but not the
+legacy.
+
+EFI uses a slightly different way of representing the time, noticeably
+the reference date is different. Year is the using the full 4-digit format.
+The Epoch is January 1st 1998. For backward compatibility reasons we don't
+expose this new way of representing time. Instead we use something very
+similar to the struct tm, i.e. struct rtc_time, as used by hwclock.
+One of the reasons for doing it this way is to allow for EFI to still evolve
+without necessarily impacting any of the user applications. The decoupling
+enables flexibility and permits writing wrapper code is ncase things change.
+
+The driver exposes two interfaces, one via the device file and a set of
+ioctl()s. The other is read-only via the /proc filesystem.
+
+As of today we don't offer a /proc/sys interface.
+
+To allow for a uniform interface between the legacy RTC and EFI time service,
+we have created the include/linux/rtc.h header file to contain only the
+"public" API of the two drivers.  The specifics of the legacy RTC are still
+in include/linux/mc146818rtc.h.
+
+
+3. Time of day service
+======================
+
+The part of the driver gives access to the time of day service of EFI.
+Two ioctl()s, compatible with the legacy RTC calls:
+
+	Read the CMOS clock::
+
+		ioctl(d, RTC_RD_TIME, &rtc);
+
+	Write the CMOS clock::
+
+		ioctl(d, RTC_SET_TIME, &rtc);
+
+The rtc is a pointer to a data structure defined in rtc.h which is close
+to a struct tm::
+
+  struct rtc_time {
+          int tm_sec;
+          int tm_min;
+          int tm_hour;
+          int tm_mday;
+          int tm_mon;
+          int tm_year;
+          int tm_wday;
+          int tm_yday;
+          int tm_isdst;
+  };
+
+The driver takes care of converting back an forth between the EFI time and
+this format.
+
+Those two ioctl()s can be exercised with the hwclock command:
+
+For reading::
+
+	# /sbin/hwclock --show
+	Mon Mar  6 15:32:32 2000  -0.910248 seconds
+
+For setting::
+
+	# /sbin/hwclock --systohc
+
+Root privileges are required to be able to set the time of day.
+
+4. Wakeup Alarm service
+=======================
+
+EFI provides an API by which one can program when a machine should wakeup,
+i.e. reboot. This is very different from the alarm provided by the legacy
+RTC which is some kind of interval timer alarm. For this reason we don't use
+the same ioctl()s to get access to the service. Instead we have
+introduced 2 news ioctl()s to the interface of an RTC.
+
+We have added 2 new ioctl()s that are specific to the EFI driver:
+
+	Read the current state of the alarm::
+
+		ioctl(d, RTC_WKALM_RD, &wkt)
+
+	Set the alarm or change its status::
+
+		ioctl(d, RTC_WKALM_SET, &wkt)
+
+The wkt structure encapsulates a struct rtc_time + 2 extra fields to get
+status information::
+
+  struct rtc_wkalrm {
+
+          unsigned char enabled; /* =1 if alarm is enabled */
+          unsigned char pending; /* =1 if alarm is pending  */
+
+          struct rtc_time time;
+  }
+
+As of today, none of the existing user-level apps supports this feature.
+However writing such a program should be hard by simply using those two
+ioctl().
+
+Root privileges are required to be able to set the alarm.
+
+5. References
+=============
+
+Checkout the following Web site for more information on EFI:
+
+http://developer.intel.com/technology/efi/
diff --git a/Documentation/arch/ia64/err_inject.rst b/Documentation/arch/ia64/err_inject.rst
new file mode 100644
index 00000000000000..900f71e93a29c5
--- /dev/null
+++ b/Documentation/arch/ia64/err_inject.rst
@@ -0,0 +1,1067 @@
+========================================
+IPF Machine Check (MC) error inject tool
+========================================
+
+IPF Machine Check (MC) error inject tool is used to inject MC
+errors from Linux. The tool is a test bed for IPF MC work flow including
+hardware correctable error handling, OS recoverable error handling, MC
+event logging, etc.
+
+The tool includes two parts: a kernel driver and a user application
+sample. The driver provides interface to PAL to inject error
+and query error injection capabilities. The driver code is in
+arch/ia64/kernel/err_inject.c. The application sample (shown below)
+provides a combination of various errors and calls the driver's interface
+(sysfs interface) to inject errors or query error injection capabilities.
+
+The tool can be used to test Intel IPF machine MC handling capabilities.
+It's especially useful for people who can not access hardware MC injection
+tool to inject error. It's also very useful to integrate with other
+software test suits to do stressful testing on IPF.
+
+Below is a sample application as part of the whole tool. The sample
+can be used as a working test tool. Or it can be expanded to include
+more features. It also can be a integrated into a library or other user
+application to have more thorough test.
+
+The sample application takes err.conf as error configuration input. GCC
+compiles the code. After you install err_inject driver, you can run
+this sample application to inject errors.
+
+Errata: Itanium 2 Processors Specification Update lists some errata against
+the pal_mc_error_inject PAL procedure. The following err.conf has been tested
+on latest Montecito PAL.
+
+err.conf::
+
+  #This is configuration file for err_inject_tool.
+  #The format of the each line is:
+  #cpu, loop, interval, err_type_info, err_struct_info, err_data_buffer
+  #where
+  #	cpu: logical cpu number the error will be inject in.
+  #	loop: times the error will be injected.
+  #	interval: In second. every so often one error is injected.
+  #	err_type_info, err_struct_info: PAL parameters.
+  #
+  #Note: All values are hex w/o or w/ 0x prefix.
+
+
+  #On cpu2, inject only total 0x10 errors, interval 5 seconds
+  #corrected, data cache, hier-2, physical addr(assigned by tool code).
+  #working on Montecito latest PAL.
+  2, 10, 5, 4101, 95
+
+  #On cpu4, inject and consume total 0x10 errors, interval 5 seconds
+  #corrected, data cache, hier-2, physical addr(assigned by tool code).
+  #working on Montecito latest PAL.
+  4, 10, 5, 4109, 95
+
+  #On cpu15, inject and consume total 0x10 errors, interval 5 seconds
+  #recoverable, DTR0, hier-2.
+  #working on Montecito latest PAL.
+  0xf, 0x10, 5, 4249, 15
+
+The sample application source code:
+
+err_injection_tool.c::
+
+  /*
+   * This program is free software; you can redistribute it and/or modify
+   * it under the terms of the GNU General Public License as published by
+   * the Free Software Foundation; either version 2 of the License, or
+   * (at your option) any later version.
+   *
+   * This program is distributed in the hope that it will be useful, but
+   * WITHOUT ANY WARRANTY; without even the implied warranty of
+   * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+   * NON INFRINGEMENT.  See the GNU General Public License for more
+   * details.
+   *
+   * You should have received a copy of the GNU General Public License
+   * along with this program; if not, write to the Free Software
+   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+   *
+   * Copyright (C) 2006 Intel Co
+   *	Fenghua Yu <fenghua.yu@intel.com>
+   *
+   */
+  #include <sys/types.h>
+  #include <sys/stat.h>
+  #include <fcntl.h>
+  #include <stdio.h>
+  #include <sched.h>
+  #include <unistd.h>
+  #include <stdlib.h>
+  #include <stdarg.h>
+  #include <string.h>
+  #include <errno.h>
+  #include <time.h>
+  #include <sys/ipc.h>
+  #include <sys/sem.h>
+  #include <sys/wait.h>
+  #include <sys/mman.h>
+  #include <sys/shm.h>
+
+  #define MAX_FN_SIZE 		256
+  #define MAX_BUF_SIZE 		256
+  #define DATA_BUF_SIZE 		256
+  #define NR_CPUS 		512
+  #define MAX_TASK_NUM		2048
+  #define MIN_INTERVAL		5	// seconds
+  #define	ERR_DATA_BUFFER_SIZE 	3	// Three 8-byte.
+  #define PARA_FIELD_NUM		5
+  #define MASK_SIZE		(NR_CPUS/64)
+  #define PATH_FORMAT "/sys/devices/system/cpu/cpu%d/err_inject/"
+
+  int sched_setaffinity(pid_t pid, unsigned int len, unsigned long *mask);
+
+  int verbose;
+  #define vbprintf if (verbose) printf
+
+  int log_info(int cpu, const char *fmt, ...)
+  {
+	FILE *log;
+	char fn[MAX_FN_SIZE];
+	char buf[MAX_BUF_SIZE];
+	va_list args;
+
+	sprintf(fn, "%d.log", cpu);
+	log=fopen(fn, "a+");
+	if (log==NULL) {
+		perror("Error open:");
+		return -1;
+	}
+
+	va_start(args, fmt);
+	vprintf(fmt, args);
+	memset(buf, 0, MAX_BUF_SIZE);
+	vsprintf(buf, fmt, args);
+	va_end(args);
+
+	fwrite(buf, sizeof(buf), 1, log);
+	fclose(log);
+
+	return 0;
+  }
+
+  typedef unsigned long u64;
+  typedef unsigned int  u32;
+
+  typedef union err_type_info_u {
+	struct {
+		u64	mode		: 3,	/* 0-2 */
+			err_inj		: 3,	/* 3-5 */
+			err_sev		: 2,	/* 6-7 */
+			err_struct	: 5,	/* 8-12 */
+			struct_hier	: 3,	/* 13-15 */
+			reserved	: 48;	/* 16-63 */
+	} err_type_info_u;
+	u64	err_type_info;
+  } err_type_info_t;
+
+  typedef union err_struct_info_u {
+	struct {
+		u64	siv		: 1,	/* 0	 */
+			c_t		: 2,	/* 1-2	 */
+			cl_p		: 3,	/* 3-5	 */
+			cl_id		: 3,	/* 6-8	 */
+			cl_dp		: 1,	/* 9	 */
+			reserved1	: 22,	/* 10-31 */
+			tiv		: 1,	/* 32	 */
+			trigger		: 4,	/* 33-36 */
+			trigger_pl 	: 3,	/* 37-39 */
+			reserved2 	: 24;	/* 40-63 */
+	} err_struct_info_cache;
+	struct {
+		u64	siv		: 1,	/* 0	 */
+			tt		: 2,	/* 1-2	 */
+			tc_tr		: 2,	/* 3-4	 */
+			tr_slot		: 8,	/* 5-12	 */
+			reserved1	: 19,	/* 13-31 */
+			tiv		: 1,	/* 32	 */
+			trigger		: 4,	/* 33-36 */
+			trigger_pl 	: 3,	/* 37-39 */
+			reserved2 	: 24;	/* 40-63 */
+	} err_struct_info_tlb;
+	struct {
+		u64	siv		: 1,	/* 0	 */
+			regfile_id	: 4,	/* 1-4	 */
+			reg_num		: 7,	/* 5-11	 */
+			reserved1	: 20,	/* 12-31 */
+			tiv		: 1,	/* 32	 */
+			trigger		: 4,	/* 33-36 */
+			trigger_pl 	: 3,	/* 37-39 */
+			reserved2 	: 24;	/* 40-63 */
+	} err_struct_info_register;
+	struct {
+		u64	reserved;
+	} err_struct_info_bus_processor_interconnect;
+	u64	err_struct_info;
+  } err_struct_info_t;
+
+  typedef union err_data_buffer_u {
+	struct {
+		u64	trigger_addr;		/* 0-63		*/
+		u64	inj_addr;		/* 64-127 	*/
+		u64	way		: 5,	/* 128-132	*/
+			index		: 20,	/* 133-152	*/
+					: 39;	/* 153-191	*/
+	} err_data_buffer_cache;
+	struct {
+		u64	trigger_addr;		/* 0-63		*/
+		u64	inj_addr;		/* 64-127 	*/
+		u64	way		: 5,	/* 128-132	*/
+			index		: 20,	/* 133-152	*/
+			reserved	: 39;	/* 153-191	*/
+	} err_data_buffer_tlb;
+	struct {
+		u64	trigger_addr;		/* 0-63		*/
+	} err_data_buffer_register;
+	struct {
+		u64	reserved;		/* 0-63		*/
+	} err_data_buffer_bus_processor_interconnect;
+	u64 err_data_buffer[ERR_DATA_BUFFER_SIZE];
+  } err_data_buffer_t;
+
+  typedef union capabilities_u {
+	struct {
+		u64	i		: 1,
+			d		: 1,
+			rv		: 1,
+			tag		: 1,
+			data		: 1,
+			mesi		: 1,
+			dp		: 1,
+			reserved1	: 3,
+			pa		: 1,
+			va		: 1,
+			wi		: 1,
+			reserved2	: 20,
+			trigger		: 1,
+			trigger_pl	: 1,
+			reserved3	: 30;
+	} capabilities_cache;
+	struct {
+		u64	d		: 1,
+			i		: 1,
+			rv		: 1,
+			tc		: 1,
+			tr		: 1,
+			reserved1	: 27,
+			trigger		: 1,
+			trigger_pl	: 1,
+			reserved2	: 30;
+	} capabilities_tlb;
+	struct {
+		u64	gr_b0		: 1,
+			gr_b1		: 1,
+			fr		: 1,
+			br		: 1,
+			pr		: 1,
+			ar		: 1,
+			cr		: 1,
+			rr		: 1,
+			pkr		: 1,
+			dbr		: 1,
+			ibr		: 1,
+			pmc		: 1,
+			pmd		: 1,
+			reserved1	: 3,
+			regnum		: 1,
+			reserved2	: 15,
+			trigger		: 1,
+			trigger_pl	: 1,
+			reserved3	: 30;
+	} capabilities_register;
+	struct {
+		u64	reserved;
+	} capabilities_bus_processor_interconnect;
+  } capabilities_t;
+
+  typedef struct resources_s {
+	u64	ibr0		: 1,
+		ibr2		: 1,
+		ibr4		: 1,
+		ibr6		: 1,
+		dbr0		: 1,
+		dbr2		: 1,
+		dbr4		: 1,
+		dbr6		: 1,
+		reserved	: 48;
+  } resources_t;
+
+
+  long get_page_size(void)
+  {
+	long page_size=sysconf(_SC_PAGESIZE);
+	return page_size;
+  }
+
+  #define PAGE_SIZE (get_page_size()==-1?0x4000:get_page_size())
+  #define SHM_SIZE (2*PAGE_SIZE*NR_CPUS)
+  #define SHM_VA 0x2000000100000000
+
+  int shmid;
+  void *shmaddr;
+
+  int create_shm(void)
+  {
+	key_t key;
+	char fn[MAX_FN_SIZE];
+
+	/* cpu0 is always existing */
+	sprintf(fn, PATH_FORMAT, 0);
+	if ((key = ftok(fn, 's')) == -1) {
+		perror("ftok");
+		return -1;
+	}
+
+	shmid = shmget(key, SHM_SIZE, 0644 | IPC_CREAT);
+	if (shmid == -1) {
+		if (errno==EEXIST) {
+			shmid = shmget(key, SHM_SIZE, 0);
+			if (shmid == -1) {
+				perror("shmget");
+				return -1;
+			}
+		}
+		else {
+			perror("shmget");
+			return -1;
+		}
+	}
+	vbprintf("shmid=%d", shmid);
+
+	/* connect to the segment: */
+	shmaddr = shmat(shmid, (void *)SHM_VA, 0);
+	if (shmaddr == (void*)-1) {
+		perror("shmat");
+		return -1;
+	}
+
+	memset(shmaddr, 0, SHM_SIZE);
+	mlock(shmaddr, SHM_SIZE);
+
+	return 0;
+  }
+
+  int free_shm()
+  {
+	munlock(shmaddr, SHM_SIZE);
+          shmdt(shmaddr);
+	semctl(shmid, 0, IPC_RMID);
+
+	return 0;
+  }
+
+  #ifdef _SEM_SEMUN_UNDEFINED
+  union semun
+  {
+	int val;
+	struct semid_ds *buf;
+	unsigned short int *array;
+	struct seminfo *__buf;
+  };
+  #endif
+
+  u32 mode=1; /* 1: physical mode; 2: virtual mode. */
+  int one_lock=1;
+  key_t key[NR_CPUS];
+  int semid[NR_CPUS];
+
+  int create_sem(int cpu)
+  {
+	union semun arg;
+	char fn[MAX_FN_SIZE];
+	int sid;
+
+	sprintf(fn, PATH_FORMAT, cpu);
+	sprintf(fn, "%s/%s", fn, "err_type_info");
+	if ((key[cpu] = ftok(fn, 'e')) == -1) {
+		perror("ftok");
+		return -1;
+	}
+
+	if (semid[cpu]!=0)
+		return 0;
+
+	/* clear old semaphore */
+	if ((sid = semget(key[cpu], 1, 0)) != -1)
+		semctl(sid, 0, IPC_RMID);
+
+	/* get one semaphore */
+	if ((semid[cpu] = semget(key[cpu], 1, IPC_CREAT | IPC_EXCL)) == -1) {
+		perror("semget");
+		printf("Please remove semaphore with key=0x%lx, then run the tool.\n",
+			(u64)key[cpu]);
+		return -1;
+	}
+
+	vbprintf("semid[%d]=0x%lx, key[%d]=%lx\n",cpu,(u64)semid[cpu],cpu,
+		(u64)key[cpu]);
+	/* initialize the semaphore to 1: */
+	arg.val = 1;
+	if (semctl(semid[cpu], 0, SETVAL, arg) == -1) {
+		perror("semctl");
+		return -1;
+	}
+
+	return 0;
+  }
+
+  static int lock(int cpu)
+  {
+	struct sembuf lock;
+
+	lock.sem_num = cpu;
+	lock.sem_op = 1;
+	semop(semid[cpu], &lock, 1);
+
+          return 0;
+  }
+
+  static int unlock(int cpu)
+  {
+	struct sembuf unlock;
+
+	unlock.sem_num = cpu;
+	unlock.sem_op = -1;
+	semop(semid[cpu], &unlock, 1);
+
+          return 0;
+  }
+
+  void free_sem(int cpu)
+  {
+	semctl(semid[cpu], 0, IPC_RMID);
+  }
+
+  int wr_multi(char *fn, unsigned long *data, int size)
+  {
+	int fd;
+	char buf[MAX_BUF_SIZE];
+	int ret;
+
+	if (size==1)
+		sprintf(buf, "%lx", *data);
+	else if (size==3)
+		sprintf(buf, "%lx,%lx,%lx", data[0], data[1], data[2]);
+	else {
+		fprintf(stderr,"write to file with wrong size!\n");
+		return -1;
+	}
+
+	fd=open(fn, O_RDWR);
+	if (!fd) {
+		perror("Error:");
+		return -1;
+	}
+	ret=write(fd, buf, sizeof(buf));
+	close(fd);
+	return ret;
+  }
+
+  int wr(char *fn, unsigned long data)
+  {
+	return wr_multi(fn, &data, 1);
+  }
+
+  int rd(char *fn, unsigned long *data)
+  {
+	int fd;
+	char buf[MAX_BUF_SIZE];
+
+	fd=open(fn, O_RDONLY);
+	if (fd<0) {
+		perror("Error:");
+		return -1;
+	}
+	read(fd, buf, MAX_BUF_SIZE);
+	*data=strtoul(buf, NULL, 16);
+	close(fd);
+	return 0;
+  }
+
+  int rd_status(char *path, int *status)
+  {
+	char fn[MAX_FN_SIZE];
+	sprintf(fn, "%s/status", path);
+	if (rd(fn, (u64*)status)<0) {
+		perror("status reading error.\n");
+		return -1;
+	}
+
+	return 0;
+  }
+
+  int rd_capabilities(char *path, u64 *capabilities)
+  {
+	char fn[MAX_FN_SIZE];
+	sprintf(fn, "%s/capabilities", path);
+	if (rd(fn, capabilities)<0) {
+		perror("capabilities reading error.\n");
+		return -1;
+	}
+
+	return 0;
+  }
+
+  int rd_all(char *path)
+  {
+	unsigned long err_type_info, err_struct_info, err_data_buffer;
+	int status;
+	unsigned long capabilities, resources;
+	char fn[MAX_FN_SIZE];
+
+	sprintf(fn, "%s/err_type_info", path);
+	if (rd(fn, &err_type_info)<0) {
+		perror("err_type_info reading error.\n");
+		return -1;
+	}
+	printf("err_type_info=%lx\n", err_type_info);
+
+	sprintf(fn, "%s/err_struct_info", path);
+	if (rd(fn, &err_struct_info)<0) {
+		perror("err_struct_info reading error.\n");
+		return -1;
+	}
+	printf("err_struct_info=%lx\n", err_struct_info);
+
+	sprintf(fn, "%s/err_data_buffer", path);
+	if (rd(fn, &err_data_buffer)<0) {
+		perror("err_data_buffer reading error.\n");
+		return -1;
+	}
+	printf("err_data_buffer=%lx\n", err_data_buffer);
+
+	sprintf(fn, "%s/status", path);
+	if (rd("status", (u64*)&status)<0) {
+		perror("status reading error.\n");
+		return -1;
+	}
+	printf("status=%d\n", status);
+
+	sprintf(fn, "%s/capabilities", path);
+	if (rd(fn,&capabilities)<0) {
+		perror("capabilities reading error.\n");
+		return -1;
+	}
+	printf("capabilities=%lx\n", capabilities);
+
+	sprintf(fn, "%s/resources", path);
+	if (rd(fn, &resources)<0) {
+		perror("resources reading error.\n");
+		return -1;
+	}
+	printf("resources=%lx\n", resources);
+
+	return 0;
+  }
+
+  int query_capabilities(char *path, err_type_info_t err_type_info,
+			u64 *capabilities)
+  {
+	char fn[MAX_FN_SIZE];
+	err_struct_info_t err_struct_info;
+	err_data_buffer_t err_data_buffer;
+
+	err_struct_info.err_struct_info=0;
+	memset(err_data_buffer.err_data_buffer, -1, ERR_DATA_BUFFER_SIZE*8);
+
+	sprintf(fn, "%s/err_type_info", path);
+	wr(fn, err_type_info.err_type_info);
+	sprintf(fn, "%s/err_struct_info", path);
+	wr(fn, 0x0);
+	sprintf(fn, "%s/err_data_buffer", path);
+	wr_multi(fn, err_data_buffer.err_data_buffer, ERR_DATA_BUFFER_SIZE);
+
+	// Fire pal_mc_error_inject procedure.
+	sprintf(fn, "%s/call_start", path);
+	wr(fn, mode);
+
+	if (rd_capabilities(path, capabilities)<0)
+		return -1;
+
+	return 0;
+  }
+
+  int query_all_capabilities()
+  {
+	int status;
+	err_type_info_t err_type_info;
+	int err_sev, err_struct, struct_hier;
+	int cap=0;
+	u64 capabilities;
+	char path[MAX_FN_SIZE];
+
+	err_type_info.err_type_info=0;			// Initial
+	err_type_info.err_type_info_u.mode=0;		// Query mode;
+	err_type_info.err_type_info_u.err_inj=0;
+
+	printf("All capabilities implemented in pal_mc_error_inject:\n");
+	sprintf(path, PATH_FORMAT ,0);
+	for (err_sev=0;err_sev<3;err_sev++)
+		for (err_struct=0;err_struct<5;err_struct++)
+			for (struct_hier=0;struct_hier<5;struct_hier++)
+	{
+		status=-1;
+		capabilities=0;
+		err_type_info.err_type_info_u.err_sev=err_sev;
+		err_type_info.err_type_info_u.err_struct=err_struct;
+		err_type_info.err_type_info_u.struct_hier=struct_hier;
+
+		if (query_capabilities(path, err_type_info, &capabilities)<0)
+			continue;
+
+		if (rd_status(path, &status)<0)
+			continue;
+
+		if (status==0) {
+			cap=1;
+			printf("For err_sev=%d, err_struct=%d, struct_hier=%d: ",
+				err_sev, err_struct, struct_hier);
+			printf("capabilities 0x%lx\n", capabilities);
+		}
+	}
+	if (!cap) {
+		printf("No capabilities supported.\n");
+		return 0;
+	}
+
+	return 0;
+  }
+
+  int err_inject(int cpu, char *path, err_type_info_t err_type_info,
+		err_struct_info_t err_struct_info,
+		err_data_buffer_t err_data_buffer)
+  {
+	int status;
+	char fn[MAX_FN_SIZE];
+
+	log_info(cpu, "err_type_info=%lx, err_struct_info=%lx, ",
+		err_type_info.err_type_info,
+		err_struct_info.err_struct_info);
+	log_info(cpu,"err_data_buffer=[%lx,%lx,%lx]\n",
+		err_data_buffer.err_data_buffer[0],
+		err_data_buffer.err_data_buffer[1],
+		err_data_buffer.err_data_buffer[2]);
+	sprintf(fn, "%s/err_type_info", path);
+	wr(fn, err_type_info.err_type_info);
+	sprintf(fn, "%s/err_struct_info", path);
+	wr(fn, err_struct_info.err_struct_info);
+	sprintf(fn, "%s/err_data_buffer", path);
+	wr_multi(fn, err_data_buffer.err_data_buffer, ERR_DATA_BUFFER_SIZE);
+
+	// Fire pal_mc_error_inject procedure.
+	sprintf(fn, "%s/call_start", path);
+	wr(fn,mode);
+
+	if (rd_status(path, &status)<0) {
+		vbprintf("fail: read status\n");
+		return -100;
+	}
+
+	if (status!=0) {
+		log_info(cpu, "fail: status=%d\n", status);
+		return status;
+	}
+
+	return status;
+  }
+
+  static int construct_data_buf(char *path, err_type_info_t err_type_info,
+		err_struct_info_t err_struct_info,
+		err_data_buffer_t *err_data_buffer,
+		void *va1)
+  {
+	char fn[MAX_FN_SIZE];
+	u64 virt_addr=0, phys_addr=0;
+
+	vbprintf("va1=%lx\n", (u64)va1);
+	memset(&err_data_buffer->err_data_buffer_cache, 0, ERR_DATA_BUFFER_SIZE*8);
+
+	switch (err_type_info.err_type_info_u.err_struct) {
+		case 1: // Cache
+			switch (err_struct_info.err_struct_info_cache.cl_id) {
+				case 1: //Virtual addr
+					err_data_buffer->err_data_buffer_cache.inj_addr=(u64)va1;
+					break;
+				case 2: //Phys addr
+					sprintf(fn, "%s/virtual_to_phys", path);
+					virt_addr=(u64)va1;
+					if (wr(fn,virt_addr)<0)
+						return -1;
+					rd(fn, &phys_addr);
+					err_data_buffer->err_data_buffer_cache.inj_addr=phys_addr;
+					break;
+				default:
+					printf("Not supported cl_id\n");
+					break;
+			}
+			break;
+		case 2: //  TLB
+			break;
+		case 3: //  Register file
+			break;
+		case 4: //  Bus/system interconnect
+		default:
+			printf("Not supported err_struct\n");
+			break;
+	}
+
+	return 0;
+  }
+
+  typedef struct {
+	u64 cpu;
+	u64 loop;
+	u64 interval;
+	u64 err_type_info;
+	u64 err_struct_info;
+	u64 err_data_buffer[ERR_DATA_BUFFER_SIZE];
+  } parameters_t;
+
+  parameters_t line_para;
+  int para;
+
+  static int empty_data_buffer(u64 *err_data_buffer)
+  {
+	int empty=1;
+	int i;
+
+	for (i=0;i<ERR_DATA_BUFFER_SIZE; i++)
+	   if (err_data_buffer[i]!=-1)
+		empty=0;
+
+	return empty;
+  }
+
+  int err_inj()
+  {
+	err_type_info_t err_type_info;
+	err_struct_info_t err_struct_info;
+	err_data_buffer_t err_data_buffer;
+	int count;
+	FILE *fp;
+	unsigned long cpu, loop, interval, err_type_info_conf, err_struct_info_conf;
+	u64 err_data_buffer_conf[ERR_DATA_BUFFER_SIZE];
+	int num;
+	int i;
+	char path[MAX_FN_SIZE];
+	parameters_t parameters[MAX_TASK_NUM]={};
+	pid_t child_pid[MAX_TASK_NUM];
+	time_t current_time;
+	int status;
+
+	if (!para) {
+	    fp=fopen("err.conf", "r");
+	    if (fp==NULL) {
+		perror("Error open err.conf");
+		return -1;
+	    }
+
+	    num=0;
+	    while (!feof(fp)) {
+		char buf[256];
+		memset(buf,0,256);
+		fgets(buf, 256, fp);
+		count=sscanf(buf, "%lx, %lx, %lx, %lx, %lx, %lx, %lx, %lx\n",
+				&cpu, &loop, &interval,&err_type_info_conf,
+				&err_struct_info_conf,
+				&err_data_buffer_conf[0],
+				&err_data_buffer_conf[1],
+				&err_data_buffer_conf[2]);
+		if (count!=PARA_FIELD_NUM+3) {
+			err_data_buffer_conf[0]=-1;
+			err_data_buffer_conf[1]=-1;
+			err_data_buffer_conf[2]=-1;
+			count=sscanf(buf, "%lx, %lx, %lx, %lx, %lx\n",
+				&cpu, &loop, &interval,&err_type_info_conf,
+				&err_struct_info_conf);
+			if (count!=PARA_FIELD_NUM)
+				continue;
+		}
+
+		parameters[num].cpu=cpu;
+		parameters[num].loop=loop;
+		parameters[num].interval= interval>MIN_INTERVAL
+					  ?interval:MIN_INTERVAL;
+		parameters[num].err_type_info=err_type_info_conf;
+		parameters[num].err_struct_info=err_struct_info_conf;
+		memcpy(parameters[num++].err_data_buffer,
+			err_data_buffer_conf,ERR_DATA_BUFFER_SIZE*8) ;
+
+		if (num>=MAX_TASK_NUM)
+			break;
+	    }
+	}
+	else {
+		parameters[0].cpu=line_para.cpu;
+		parameters[0].loop=line_para.loop;
+		parameters[0].interval= line_para.interval>MIN_INTERVAL
+					  ?line_para.interval:MIN_INTERVAL;
+		parameters[0].err_type_info=line_para.err_type_info;
+		parameters[0].err_struct_info=line_para.err_struct_info;
+		memcpy(parameters[0].err_data_buffer,
+			line_para.err_data_buffer,ERR_DATA_BUFFER_SIZE*8) ;
+
+		num=1;
+	}
+
+	/* Create semaphore: If one_lock, one semaphore for all processors.
+	   Otherwise, one semaphore for each processor. */
+	if (one_lock) {
+		if (create_sem(0)) {
+			printf("Can not create semaphore...exit\n");
+			free_sem(0);
+			return -1;
+		}
+	}
+	else {
+		for (i=0;i<num;i++) {
+		   if (create_sem(parameters[i].cpu)) {
+			printf("Can not create semaphore for cpu%d...exit\n",i);
+			free_sem(parameters[num].cpu);
+			return -1;
+		   }
+		}
+	}
+
+	/* Create a shm segment which will be used to inject/consume errors on.*/
+	if (create_shm()==-1) {
+		printf("Error to create shm...exit\n");
+		return -1;
+	}
+
+	for (i=0;i<num;i++) {
+		pid_t pid;
+
+		current_time=time(NULL);
+		log_info(parameters[i].cpu, "\nBegine at %s", ctime(&current_time));
+		log_info(parameters[i].cpu, "Configurations:\n");
+		log_info(parameters[i].cpu,"On cpu%ld: loop=%lx, interval=%lx(s)",
+			parameters[i].cpu,
+			parameters[i].loop,
+			parameters[i].interval);
+		log_info(parameters[i].cpu," err_type_info=%lx,err_struct_info=%lx\n",
+			parameters[i].err_type_info,
+			parameters[i].err_struct_info);
+
+		sprintf(path, PATH_FORMAT, (int)parameters[i].cpu);
+		err_type_info.err_type_info=parameters[i].err_type_info;
+		err_struct_info.err_struct_info=parameters[i].err_struct_info;
+		memcpy(err_data_buffer.err_data_buffer,
+			parameters[i].err_data_buffer,
+			ERR_DATA_BUFFER_SIZE*8);
+
+		pid=fork();
+		if (pid==0) {
+			unsigned long mask[MASK_SIZE];
+			int j, k;
+
+			void *va1, *va2;
+
+			/* Allocate two memory areas va1 and va2 in shm */
+			va1=shmaddr+parameters[i].cpu*PAGE_SIZE;
+			va2=shmaddr+parameters[i].cpu*PAGE_SIZE+PAGE_SIZE;
+
+			vbprintf("va1=%lx, va2=%lx\n", (u64)va1, (u64)va2);
+			memset(va1, 0x1, PAGE_SIZE);
+			memset(va2, 0x2, PAGE_SIZE);
+
+			if (empty_data_buffer(err_data_buffer.err_data_buffer))
+				/* If not specified yet, construct data buffer
+				 * with va1
+				 */
+				construct_data_buf(path, err_type_info,
+					err_struct_info, &err_data_buffer,va1);
+
+			for (j=0;j<MASK_SIZE;j++)
+				mask[j]=0;
+
+			cpu=parameters[i].cpu;
+			k = cpu%64;
+			j = cpu/64;
+			mask[j] = 1UL << k;
+
+			if (sched_setaffinity(0, MASK_SIZE*8, mask)==-1) {
+				perror("Error sched_setaffinity:");
+				return -1;
+			}
+
+			for (j=0; j<parameters[i].loop; j++) {
+				log_info(parameters[i].cpu,"Injection ");
+				log_info(parameters[i].cpu,"on cpu%ld: #%d/%ld ",
+
+					parameters[i].cpu,j+1, parameters[i].loop);
+
+				/* Hold the lock */
+				if (one_lock)
+					lock(0);
+				else
+				/* Hold lock on this cpu */
+					lock(parameters[i].cpu);
+
+				if ((status=err_inject(parameters[i].cpu,
+					   path, err_type_info,
+					   err_struct_info, err_data_buffer))
+					   ==0) {
+					/* consume the error for "inject only"*/
+					memcpy(va2, va1, PAGE_SIZE);
+					memcpy(va1, va2, PAGE_SIZE);
+					log_info(parameters[i].cpu,
+						"successful\n");
+				}
+				else {
+					log_info(parameters[i].cpu,"fail:");
+					log_info(parameters[i].cpu,
+						"status=%d\n", status);
+					unlock(parameters[i].cpu);
+					break;
+				}
+				if (one_lock)
+				/* Release the lock */
+					unlock(0);
+				/* Release lock on this cpu */
+				else
+					unlock(parameters[i].cpu);
+
+				if (j < parameters[i].loop-1)
+					sleep(parameters[i].interval);
+			}
+			current_time=time(NULL);
+			log_info(parameters[i].cpu, "Done at %s", ctime(&current_time));
+			return 0;
+		}
+		else if (pid<0) {
+			perror("Error fork:");
+			continue;
+		}
+		child_pid[i]=pid;
+	}
+	for (i=0;i<num;i++)
+		waitpid(child_pid[i], NULL, 0);
+
+	if (one_lock)
+		free_sem(0);
+	else
+		for (i=0;i<num;i++)
+			free_sem(parameters[i].cpu);
+
+	printf("All done.\n");
+
+	return 0;
+  }
+
+  void help()
+  {
+	printf("err_inject_tool:\n");
+	printf("\t-q: query all capabilities. default: off\n");
+	printf("\t-m: procedure mode. 1: physical 2: virtual. default: 1\n");
+	printf("\t-i: inject errors. default: off\n");
+	printf("\t-l: one lock per cpu. default: one lock for all\n");
+	printf("\t-e: error parameters:\n");
+	printf("\t\tcpu,loop,interval,err_type_info,err_struct_info[,err_data_buffer[0],err_data_buffer[1],err_data_buffer[2]]\n");
+	printf("\t\t   cpu: logical cpu number the error will be inject in.\n");
+	printf("\t\t   loop: times the error will be injected.\n");
+	printf("\t\t   interval: In second. every so often one error is injected.\n");
+	printf("\t\t   err_type_info, err_struct_info: PAL parameters.\n");
+	printf("\t\t   err_data_buffer: PAL parameter. Optional. If not present,\n");
+	printf("\t\t                    it's constructed by tool automatically. Be\n");
+	printf("\t\t                    careful to provide err_data_buffer and make\n");
+	printf("\t\t                    sure it's working with the environment.\n");
+	printf("\t    Note:no space between error parameters.\n");
+	printf("\t    default: Take error parameters from err.conf instead of command line.\n");
+	printf("\t-v: verbose. default: off\n");
+	printf("\t-h: help\n\n");
+	printf("The tool will take err.conf file as ");
+	printf("input to inject single or multiple errors ");
+	printf("on one or multiple cpus in parallel.\n");
+  }
+
+  int main(int argc, char **argv)
+  {
+	char c;
+	int do_err_inj=0;
+	int do_query_all=0;
+	int count;
+	u32 m;
+
+	/* Default one lock for all cpu's */
+	one_lock=1;
+	while ((c = getopt(argc, argv, "m:iqvhle:")) != EOF)
+		switch (c) {
+			case 'm':	/* Procedure mode. 1: phys 2: virt */
+				count=sscanf(optarg, "%x", &m);
+				if (count!=1 || (m!=1 && m!=2)) {
+					printf("Wrong mode number.\n");
+					help();
+					return -1;
+				}
+				mode=m;
+				break;
+			case 'i':	/* Inject errors */
+				do_err_inj=1;
+				break;
+			case 'q':	/* Query */
+				do_query_all=1;
+				break;
+			case 'v':	/* Verbose */
+				verbose=1;
+				break;
+			case 'l':	/* One lock per cpu */
+				one_lock=0;
+				break;
+			case 'e':	/* error arguments */
+				/* Take parameters:
+				 * #cpu, loop, interval, err_type_info, err_struct_info[, err_data_buffer]
+				 * err_data_buffer is optional. Recommend not to specify
+				 * err_data_buffer. Better to use tool to generate it.
+				 */
+				count=sscanf(optarg,
+					"%lx, %lx, %lx, %lx, %lx, %lx, %lx, %lx\n",
+					&line_para.cpu,
+					&line_para.loop,
+					&line_para.interval,
+					&line_para.err_type_info,
+					&line_para.err_struct_info,
+					&line_para.err_data_buffer[0],
+					&line_para.err_data_buffer[1],
+					&line_para.err_data_buffer[2]);
+				if (count!=PARA_FIELD_NUM+3) {
+				    line_para.err_data_buffer[0]=-1,
+				    line_para.err_data_buffer[1]=-1,
+				    line_para.err_data_buffer[2]=-1;
+				    count=sscanf(optarg, "%lx, %lx, %lx, %lx, %lx\n",
+						&line_para.cpu,
+						&line_para.loop,
+						&line_para.interval,
+						&line_para.err_type_info,
+						&line_para.err_struct_info);
+				    if (count!=PARA_FIELD_NUM) {
+					printf("Wrong error arguments.\n");
+					help();
+					return -1;
+				    }
+				}
+				para=1;
+				break;
+			continue;
+				break;
+			case 'h':
+				help();
+				return 0;
+			default:
+				break;
+		}
+
+	if (do_query_all)
+		query_all_capabilities();
+	if (do_err_inj)
+		err_inj();
+
+	if (!do_query_all &&  !do_err_inj)
+		help();
+
+	return 0;
+  }
diff --git a/Documentation/arch/ia64/features.rst b/Documentation/arch/ia64/features.rst
new file mode 100644
index 00000000000000..d7226fdcf5f8c0
--- /dev/null
+++ b/Documentation/arch/ia64/features.rst
@@ -0,0 +1,3 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. kernel-feat:: $srctree/Documentation/features ia64
diff --git a/Documentation/arch/ia64/fsys.rst b/Documentation/arch/ia64/fsys.rst
new file mode 100644
index 00000000000000..a702d2cc94b630
--- /dev/null
+++ b/Documentation/arch/ia64/fsys.rst
@@ -0,0 +1,303 @@
+===================================
+Light-weight System Calls for IA-64
+===================================
+
+		        Started: 13-Jan-2003
+
+		    Last update: 27-Sep-2003
+
+	              David Mosberger-Tang
+		      <davidm@hpl.hp.com>
+
+Using the "epc" instruction effectively introduces a new mode of
+execution to the ia64 linux kernel.  We call this mode the
+"fsys-mode".  To recap, the normal states of execution are:
+
+  - kernel mode:
+	Both the register stack and the memory stack have been
+	switched over to kernel memory.  The user-level state is saved
+	in a pt-regs structure at the top of the kernel memory stack.
+
+  - user mode:
+	Both the register stack and the kernel stack are in
+	user memory.  The user-level state is contained in the
+	CPU registers.
+
+  - bank 0 interruption-handling mode:
+	This is the non-interruptible state which all
+	interruption-handlers start execution in.  The user-level
+	state remains in the CPU registers and some kernel state may
+	be stored in bank 0 of registers r16-r31.
+
+In contrast, fsys-mode has the following special properties:
+
+  - execution is at privilege level 0 (most-privileged)
+
+  - CPU registers may contain a mixture of user-level and kernel-level
+    state (it is the responsibility of the kernel to ensure that no
+    security-sensitive kernel-level state is leaked back to
+    user-level)
+
+  - execution is interruptible and preemptible (an fsys-mode handler
+    can disable interrupts and avoid all other interruption-sources
+    to avoid preemption)
+
+  - neither the memory-stack nor the register-stack can be trusted while
+    in fsys-mode (they point to the user-level stacks, which may
+    be invalid, or completely bogus addresses)
+
+In summary, fsys-mode is much more similar to running in user-mode
+than it is to running in kernel-mode.  Of course, given that the
+privilege level is at level 0, this means that fsys-mode requires some
+care (see below).
+
+
+How to tell fsys-mode
+=====================
+
+Linux operates in fsys-mode when (a) the privilege level is 0 (most
+privileged) and (b) the stacks have NOT been switched to kernel memory
+yet.  For convenience, the header file <asm-ia64/ptrace.h> provides
+three macros::
+
+	user_mode(regs)
+	user_stack(task,regs)
+	fsys_mode(task,regs)
+
+The "regs" argument is a pointer to a pt_regs structure.  The "task"
+argument is a pointer to the task structure to which the "regs"
+pointer belongs to.  user_mode() returns TRUE if the CPU state pointed
+to by "regs" was executing in user mode (privilege level 3).
+user_stack() returns TRUE if the state pointed to by "regs" was
+executing on the user-level stack(s).  Finally, fsys_mode() returns
+TRUE if the CPU state pointed to by "regs" was executing in fsys-mode.
+The fsys_mode() macro is equivalent to the expression::
+
+	!user_mode(regs) && user_stack(task,regs)
+
+How to write an fsyscall handler
+================================
+
+The file arch/ia64/kernel/fsys.S contains a table of fsyscall-handlers
+(fsyscall_table).  This table contains one entry for each system call.
+By default, a system call is handled by fsys_fallback_syscall().  This
+routine takes care of entering (full) kernel mode and calling the
+normal Linux system call handler.  For performance-critical system
+calls, it is possible to write a hand-tuned fsyscall_handler.  For
+example, fsys.S contains fsys_getpid(), which is a hand-tuned version
+of the getpid() system call.
+
+The entry and exit-state of an fsyscall handler is as follows:
+
+Machine state on entry to fsyscall handler
+------------------------------------------
+
+  ========= ===============================================================
+  r10	    0
+  r11	    saved ar.pfs (a user-level value)
+  r15	    system call number
+  r16	    "current" task pointer (in normal kernel-mode, this is in r13)
+  r32-r39   system call arguments
+  b6	    return address (a user-level value)
+  ar.pfs    previous frame-state (a user-level value)
+  PSR.be    cleared to zero (i.e., little-endian byte order is in effect)
+  -         all other registers may contain values passed in from user-mode
+  ========= ===============================================================
+
+Required machine state on exit to fsyscall handler
+--------------------------------------------------
+
+  ========= ===========================================================
+  r11	    saved ar.pfs (as passed into the fsyscall handler)
+  r15	    system call number (as passed into the fsyscall handler)
+  r32-r39   system call arguments (as passed into the fsyscall handler)
+  b6	    return address (as passed into the fsyscall handler)
+  ar.pfs    previous frame-state (as passed into the fsyscall handler)
+  ========= ===========================================================
+
+Fsyscall handlers can execute with very little overhead, but with that
+speed comes a set of restrictions:
+
+ * Fsyscall-handlers MUST check for any pending work in the flags
+   member of the thread-info structure and if any of the
+   TIF_ALLWORK_MASK flags are set, the handler needs to fall back on
+   doing a full system call (by calling fsys_fallback_syscall).
+
+ * Fsyscall-handlers MUST preserve incoming arguments (r32-r39, r11,
+   r15, b6, and ar.pfs) because they will be needed in case of a
+   system call restart.  Of course, all "preserved" registers also
+   must be preserved, in accordance to the normal calling conventions.
+
+ * Fsyscall-handlers MUST check argument registers for containing a
+   NaT value before using them in any way that could trigger a
+   NaT-consumption fault.  If a system call argument is found to
+   contain a NaT value, an fsyscall-handler may return immediately
+   with r8=EINVAL, r10=-1.
+
+ * Fsyscall-handlers MUST NOT use the "alloc" instruction or perform
+   any other operation that would trigger mandatory RSE
+   (register-stack engine) traffic.
+
+ * Fsyscall-handlers MUST NOT write to any stacked registers because
+   it is not safe to assume that user-level called a handler with the
+   proper number of arguments.
+
+ * Fsyscall-handlers need to be careful when accessing per-CPU variables:
+   unless proper safe-guards are taken (e.g., interruptions are avoided),
+   execution may be pre-empted and resumed on another CPU at any given
+   time.
+
+ * Fsyscall-handlers must be careful not to leak sensitive kernel'
+   information back to user-level.  In particular, before returning to
+   user-level, care needs to be taken to clear any scratch registers
+   that could contain sensitive information (note that the current
+   task pointer is not considered sensitive: it's already exposed
+   through ar.k6).
+
+ * Fsyscall-handlers MUST NOT access user-memory without first
+   validating access-permission (this can be done typically via
+   probe.r.fault and/or probe.w.fault) and without guarding against
+   memory access exceptions (this can be done with the EX() macros
+   defined by asmmacro.h).
+
+The above restrictions may seem draconian, but remember that it's
+possible to trade off some of the restrictions by paying a slightly
+higher overhead.  For example, if an fsyscall-handler could benefit
+from the shadow register bank, it could temporarily disable PSR.i and
+PSR.ic, switch to bank 0 (bsw.0) and then use the shadow registers as
+needed.  In other words, following the above rules yields extremely
+fast system call execution (while fully preserving system call
+semantics), but there is also a lot of flexibility in handling more
+complicated cases.
+
+Signal handling
+===============
+
+The delivery of (asynchronous) signals must be delayed until fsys-mode
+is exited.  This is accomplished with the help of the lower-privilege
+transfer trap: arch/ia64/kernel/process.c:do_notify_resume_user()
+checks whether the interrupted task was in fsys-mode and, if so, sets
+PSR.lp and returns immediately.  When fsys-mode is exited via the
+"br.ret" instruction that lowers the privilege level, a trap will
+occur.  The trap handler clears PSR.lp again and returns immediately.
+The kernel exit path then checks for and delivers any pending signals.
+
+PSR Handling
+============
+
+The "epc" instruction doesn't change the contents of PSR at all.  This
+is in contrast to a regular interruption, which clears almost all
+bits.  Because of that, some care needs to be taken to ensure things
+work as expected.  The following discussion describes how each PSR bit
+is handled.
+
+======= =======================================================================
+PSR.be	Cleared when entering fsys-mode.  A srlz.d instruction is used
+	to ensure the CPU is in little-endian mode before the first
+	load/store instruction is executed.  PSR.be is normally NOT
+	restored upon return from an fsys-mode handler.  In other
+	words, user-level code must not rely on PSR.be being preserved
+	across a system call.
+PSR.up	Unchanged.
+PSR.ac	Unchanged.
+PSR.mfl Unchanged.  Note: fsys-mode handlers must not write-registers!
+PSR.mfh	Unchanged.  Note: fsys-mode handlers must not write-registers!
+PSR.ic	Unchanged.  Note: fsys-mode handlers can clear the bit, if needed.
+PSR.i	Unchanged.  Note: fsys-mode handlers can clear the bit, if needed.
+PSR.pk	Unchanged.
+PSR.dt	Unchanged.
+PSR.dfl	Unchanged.  Note: fsys-mode handlers must not write-registers!
+PSR.dfh	Unchanged.  Note: fsys-mode handlers must not write-registers!
+PSR.sp	Unchanged.
+PSR.pp	Unchanged.
+PSR.di	Unchanged.
+PSR.si	Unchanged.
+PSR.db	Unchanged.  The kernel prevents user-level from setting a hardware
+	breakpoint that triggers at any privilege level other than
+	3 (user-mode).
+PSR.lp	Unchanged.
+PSR.tb	Lazy redirect.  If a taken-branch trap occurs while in
+	fsys-mode, the trap-handler modifies the saved machine state
+	such that execution resumes in the gate page at
+	syscall_via_break(), with privilege level 3.  Note: the
+	taken branch would occur on the branch invoking the
+	fsyscall-handler, at which point, by definition, a syscall
+	restart is still safe.  If the system call number is invalid,
+	the fsys-mode handler will return directly to user-level.  This
+	return will trigger a taken-branch trap, but since the trap is
+	taken _after_ restoring the privilege level, the CPU has already
+	left fsys-mode, so no special treatment is needed.
+PSR.rt	Unchanged.
+PSR.cpl	Cleared to 0.
+PSR.is	Unchanged (guaranteed to be 0 on entry to the gate page).
+PSR.mc	Unchanged.
+PSR.it	Unchanged (guaranteed to be 1).
+PSR.id	Unchanged.  Note: the ia64 linux kernel never sets this bit.
+PSR.da	Unchanged.  Note: the ia64 linux kernel never sets this bit.
+PSR.dd	Unchanged.  Note: the ia64 linux kernel never sets this bit.
+PSR.ss	Lazy redirect.  If set, "epc" will cause a Single Step Trap to
+	be taken.  The trap handler then modifies the saved machine
+	state such that execution resumes in the gate page at
+	syscall_via_break(), with privilege level 3.
+PSR.ri	Unchanged.
+PSR.ed	Unchanged.  Note: This bit could only have an effect if an fsys-mode
+	handler performed a speculative load that gets NaTted.  If so, this
+	would be the normal & expected behavior, so no special treatment is
+	needed.
+PSR.bn	Unchanged.  Note: fsys-mode handlers may clear the bit, if needed.
+	Doing so requires clearing PSR.i and PSR.ic as well.
+PSR.ia	Unchanged.  Note: the ia64 linux kernel never sets this bit.
+======= =======================================================================
+
+Using fast system calls
+=======================
+
+To use fast system calls, userspace applications need simply call
+__kernel_syscall_via_epc().  For example
+
+-- example fgettimeofday() call --
+
+-- fgettimeofday.S --
+
+::
+
+  #include <asm/asmmacro.h>
+
+  GLOBAL_ENTRY(fgettimeofday)
+  .prologue
+  .save ar.pfs, r11
+  mov r11 = ar.pfs
+  .body
+
+  mov r2 = 0xa000000000020660;;  // gate address
+			       // found by inspection of System.map for the
+			       // __kernel_syscall_via_epc() function.  See
+			       // below for how to do this for real.
+
+  mov b7 = r2
+  mov r15 = 1087		       // gettimeofday syscall
+  ;;
+  br.call.sptk.many b6 = b7
+  ;;
+
+  .restore sp
+
+  mov ar.pfs = r11
+  br.ret.sptk.many rp;;	      // return to caller
+  END(fgettimeofday)
+
+-- end fgettimeofday.S --
+
+In reality, getting the gate address is accomplished by two extra
+values passed via the ELF auxiliary vector (include/asm-ia64/elf.h)
+
+ * AT_SYSINFO : is the address of __kernel_syscall_via_epc()
+ * AT_SYSINFO_EHDR : is the address of the kernel gate ELF DSO
+
+The ELF DSO is a pre-linked library that is mapped in by the kernel at
+the gate page.  It is a proper ELF shared object so, with a dynamic
+loader that recognises the library, you should be able to make calls to
+the exported functions within it as with any other shared library.
+AT_SYSINFO points into the kernel DSO at the
+__kernel_syscall_via_epc() function for historical reasons (it was
+used before the kernel DSO) and as a convenience.
diff --git a/Documentation/arch/ia64/ia64.rst b/Documentation/arch/ia64/ia64.rst
new file mode 100644
index 00000000000000..b725019a94927f
--- /dev/null
+++ b/Documentation/arch/ia64/ia64.rst
@@ -0,0 +1,49 @@
+===========================================
+Linux kernel release for the IA-64 Platform
+===========================================
+
+   These are the release notes for Linux since version 2.4 for IA-64
+   platform.  This document provides information specific to IA-64
+   ONLY, to get additional information about the Linux kernel also
+   read the original Linux README provided with the kernel.
+
+Installing the Kernel
+=====================
+
+ - IA-64 kernel installation is the same as the other platforms, see
+   original README for details.
+
+
+Software Requirements
+=====================
+
+   Compiling and running this kernel requires an IA-64 compliant GCC
+   compiler.  And various software packages also compiled with an
+   IA-64 compliant GCC compiler.
+
+
+Configuring the Kernel
+======================
+
+   Configuration is the same, see original README for details.
+
+
+Compiling the Kernel:
+
+ - Compiling this kernel doesn't differ from other platform so read
+   the original README for details BUT make sure you have an IA-64
+   compliant GCC compiler.
+
+IA-64 Specifics
+===============
+
+ - General issues:
+
+    * Hardly any performance tuning has been done. Obvious targets
+      include the library routines (IP checksum, etc.). Less
+      obvious targets include making sure we don't flush the TLB
+      needlessly, etc.
+
+    * SMP locks cleanup/optimization
+
+    * IA32 support.  Currently experimental.  It mostly works.
diff --git a/Documentation/arch/ia64/index.rst b/Documentation/arch/ia64/index.rst
new file mode 100644
index 00000000000000..761f2154dfa27a
--- /dev/null
+++ b/Documentation/arch/ia64/index.rst
@@ -0,0 +1,19 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================
+IA-64 Architecture
+==================
+
+.. toctree::
+   :maxdepth: 1
+
+   ia64
+   aliasing
+   efirtc
+   err_inject
+   fsys
+   irq-redir
+   mca
+   serial
+
+   features
diff --git a/Documentation/arch/ia64/irq-redir.rst b/Documentation/arch/ia64/irq-redir.rst
new file mode 100644
index 00000000000000..6bbbbe4f73efc4
--- /dev/null
+++ b/Documentation/arch/ia64/irq-redir.rst
@@ -0,0 +1,80 @@
+==============================
+IRQ affinity on IA64 platforms
+==============================
+
+07.01.2002, Erich Focht <efocht@ess.nec.de>
+
+
+By writing to /proc/irq/IRQ#/smp_affinity the interrupt routing can be
+controlled. The behavior on IA64 platforms is slightly different from
+that described in Documentation/core-api/irq/irq-affinity.rst for i386 systems.
+
+Because of the usage of SAPIC mode and physical destination mode the
+IRQ target is one particular CPU and cannot be a mask of several
+CPUs. Only the first non-zero bit is taken into account.
+
+
+Usage examples
+==============
+
+The target CPU has to be specified as a hexadecimal CPU mask. The
+first non-zero bit is the selected CPU. This format has been kept for
+compatibility reasons with i386.
+
+Set the delivery mode of interrupt 41 to fixed and route the
+interrupts to CPU #3 (logical CPU number) (2^3=0x08)::
+
+     echo "8" >/proc/irq/41/smp_affinity
+
+Set the default route for IRQ number 41 to CPU 6 in lowest priority
+delivery mode (redirectable)::
+
+     echo "r 40" >/proc/irq/41/smp_affinity
+
+The output of the command::
+
+     cat /proc/irq/IRQ#/smp_affinity
+
+gives the target CPU mask for the specified interrupt vector. If the CPU
+mask is preceded by the character "r", the interrupt is redirectable
+(i.e. lowest priority mode routing is used), otherwise its route is
+fixed.
+
+
+
+Initialization and default behavior
+===================================
+
+If the platform features IRQ redirection (info provided by SAL) all
+IO-SAPIC interrupts are initialized with CPU#0 as their default target
+and the routing is the so called "lowest priority mode" (actually
+fixed SAPIC mode with hint). The XTP chipset registers are used as hints
+for the IRQ routing. Currently in Linux XTP registers can have three
+values:
+
+	- minimal for an idle task,
+	- normal if any other task runs,
+	- maximal if the CPU is going to be switched off.
+
+The IRQ is routed to the CPU with lowest XTP register value, the
+search begins at the default CPU. Therefore most of the interrupts
+will be handled by CPU #0.
+
+If the platform doesn't feature interrupt redirection IOSAPIC fixed
+routing is used. The target CPUs are distributed in a round robin
+manner. IRQs will be routed only to the selected target CPUs. Check
+with::
+
+        cat /proc/interrupts
+
+
+
+Comments
+========
+
+On large (multi-node) systems it is recommended to route the IRQs to
+the node to which the corresponding device is connected.
+For systems like the NEC AzusA we get IRQ node-affinity for free. This
+is because usually the chipsets on each node redirect the interrupts
+only to their own CPUs (as they cannot see the XTP registers on the
+other nodes).
diff --git a/Documentation/arch/ia64/mca.rst b/Documentation/arch/ia64/mca.rst
new file mode 100644
index 00000000000000..08270bba44a443
--- /dev/null
+++ b/Documentation/arch/ia64/mca.rst
@@ -0,0 +1,198 @@
+=============================================================
+An ad-hoc collection of notes on IA64 MCA and INIT processing
+=============================================================
+
+Feel free to update it with notes about any area that is not clear.
+
+---
+
+MCA/INIT are completely asynchronous.  They can occur at any time, when
+the OS is in any state.  Including when one of the cpus is already
+holding a spinlock.  Trying to get any lock from MCA/INIT state is
+asking for deadlock.  Also the state of structures that are protected
+by locks is indeterminate, including linked lists.
+
+---
+
+The complicated ia64 MCA process.  All of this is mandated by Intel's
+specification for ia64 SAL, error recovery and unwind, it is not as
+if we have a choice here.
+
+* MCA occurs on one cpu, usually due to a double bit memory error.
+  This is the monarch cpu.
+
+* SAL sends an MCA rendezvous interrupt (which is a normal interrupt)
+  to all the other cpus, the slaves.
+
+* Slave cpus that receive the MCA interrupt call down into SAL, they
+  end up spinning disabled while the MCA is being serviced.
+
+* If any slave cpu was already spinning disabled when the MCA occurred
+  then it cannot service the MCA interrupt.  SAL waits ~20 seconds then
+  sends an unmaskable INIT event to the slave cpus that have not
+  already rendezvoused.
+
+* Because MCA/INIT can be delivered at any time, including when the cpu
+  is down in PAL in physical mode, the registers at the time of the
+  event are _completely_ undefined.  In particular the MCA/INIT
+  handlers cannot rely on the thread pointer, PAL physical mode can
+  (and does) modify TP.  It is allowed to do that as long as it resets
+  TP on return.  However MCA/INIT events expose us to these PAL
+  internal TP changes.  Hence curr_task().
+
+* If an MCA/INIT event occurs while the kernel was running (not user
+  space) and the kernel has called PAL then the MCA/INIT handler cannot
+  assume that the kernel stack is in a fit state to be used.  Mainly
+  because PAL may or may not maintain the stack pointer internally.
+  Because the MCA/INIT handlers cannot trust the kernel stack, they
+  have to use their own, per-cpu stacks.  The MCA/INIT stacks are
+  preformatted with just enough task state to let the relevant handlers
+  do their job.
+
+* Unlike most other architectures, the ia64 struct task is embedded in
+  the kernel stack[1].  So switching to a new kernel stack means that
+  we switch to a new task as well.  Because various bits of the kernel
+  assume that current points into the struct task, switching to a new
+  stack also means a new value for current.
+
+* Once all slaves have rendezvoused and are spinning disabled, the
+  monarch is entered.  The monarch now tries to diagnose the problem
+  and decide if it can recover or not.
+
+* Part of the monarch's job is to look at the state of all the other
+  tasks.  The only way to do that on ia64 is to call the unwinder,
+  as mandated by Intel.
+
+* The starting point for the unwind depends on whether a task is
+  running or not.  That is, whether it is on a cpu or is blocked.  The
+  monarch has to determine whether or not a task is on a cpu before it
+  knows how to start unwinding it.  The tasks that received an MCA or
+  INIT event are no longer running, they have been converted to blocked
+  tasks.  But (and its a big but), the cpus that received the MCA
+  rendezvous interrupt are still running on their normal kernel stacks!
+
+* To distinguish between these two cases, the monarch must know which
+  tasks are on a cpu and which are not.  Hence each slave cpu that
+  switches to an MCA/INIT stack, registers its new stack using
+  set_curr_task(), so the monarch can tell that the _original_ task is
+  no longer running on that cpu.  That gives us a decent chance of
+  getting a valid backtrace of the _original_ task.
+
+* MCA/INIT can be nested, to a depth of 2 on any cpu.  In the case of a
+  nested error, we want diagnostics on the MCA/INIT handler that
+  failed, not on the task that was originally running.  Again this
+  requires set_curr_task() so the MCA/INIT handlers can register their
+  own stack as running on that cpu.  Then a recursive error gets a
+  trace of the failing handler's "task".
+
+[1]
+    My (Keith Owens) original design called for ia64 to separate its
+    struct task and the kernel stacks.  Then the MCA/INIT data would be
+    chained stacks like i386 interrupt stacks.  But that required
+    radical surgery on the rest of ia64, plus extra hard wired TLB
+    entries with its associated performance degradation.  David
+    Mosberger vetoed that approach.  Which meant that separate kernel
+    stacks meant separate "tasks" for the MCA/INIT handlers.
+
+---
+
+INIT is less complicated than MCA.  Pressing the nmi button or using
+the equivalent command on the management console sends INIT to all
+cpus.  SAL picks one of the cpus as the monarch and the rest are
+slaves.  All the OS INIT handlers are entered at approximately the same
+time.  The OS monarch prints the state of all tasks and returns, after
+which the slaves return and the system resumes.
+
+At least that is what is supposed to happen.  Alas there are broken
+versions of SAL out there.  Some drive all the cpus as monarchs.  Some
+drive them all as slaves.  Some drive one cpu as monarch, wait for that
+cpu to return from the OS then drive the rest as slaves.  Some versions
+of SAL cannot even cope with returning from the OS, they spin inside
+SAL on resume.  The OS INIT code has workarounds for some of these
+broken SAL symptoms, but some simply cannot be fixed from the OS side.
+
+---
+
+The scheduler hooks used by ia64 (curr_task, set_curr_task) are layer
+violations.  Unfortunately MCA/INIT start off as massive layer
+violations (can occur at _any_ time) and they build from there.
+
+At least ia64 makes an attempt at recovering from hardware errors, but
+it is a difficult problem because of the asynchronous nature of these
+errors.  When processing an unmaskable interrupt we sometimes need
+special code to cope with our inability to take any locks.
+
+---
+
+How is ia64 MCA/INIT different from x86 NMI?
+
+* x86 NMI typically gets delivered to one cpu.  MCA/INIT gets sent to
+  all cpus.
+
+* x86 NMI cannot be nested.  MCA/INIT can be nested, to a depth of 2
+  per cpu.
+
+* x86 has a separate struct task which points to one of multiple kernel
+  stacks.  ia64 has the struct task embedded in the single kernel
+  stack, so switching stack means switching task.
+
+* x86 does not call the BIOS so the NMI handler does not have to worry
+  about any registers having changed.  MCA/INIT can occur while the cpu
+  is in PAL in physical mode, with undefined registers and an undefined
+  kernel stack.
+
+* i386 backtrace is not very sensitive to whether a process is running
+  or not.  ia64 unwind is very, very sensitive to whether a process is
+  running or not.
+
+---
+
+What happens when MCA/INIT is delivered what a cpu is running user
+space code?
+
+The user mode registers are stored in the RSE area of the MCA/INIT on
+entry to the OS and are restored from there on return to SAL, so user
+mode registers are preserved across a recoverable MCA/INIT.  Since the
+OS has no idea what unwind data is available for the user space stack,
+MCA/INIT never tries to backtrace user space.  Which means that the OS
+does not bother making the user space process look like a blocked task,
+i.e. the OS does not copy pt_regs and switch_stack to the user space
+stack.  Also the OS has no idea how big the user space RSE and memory
+stacks are, which makes it too risky to copy the saved state to a user
+mode stack.
+
+---
+
+How do we get a backtrace on the tasks that were running when MCA/INIT
+was delivered?
+
+mca.c:::ia64_mca_modify_original_stack().  That identifies and
+verifies the original kernel stack, copies the dirty registers from
+the MCA/INIT stack's RSE to the original stack's RSE, copies the
+skeleton struct pt_regs and switch_stack to the original stack, fills
+in the skeleton structures from the PAL minstate area and updates the
+original stack's thread.ksp.  That makes the original stack look
+exactly like any other blocked task, i.e. it now appears to be
+sleeping.  To get a backtrace, just start with thread.ksp for the
+original task and unwind like any other sleeping task.
+
+---
+
+How do we identify the tasks that were running when MCA/INIT was
+delivered?
+
+If the previous task has been verified and converted to a blocked
+state, then sos->prev_task on the MCA/INIT stack is updated to point to
+the previous task.  You can look at that field in dumps or debuggers.
+To help distinguish between the handler and the original tasks,
+handlers have _TIF_MCA_INIT set in thread_info.flags.
+
+The sos data is always in the MCA/INIT handler stack, at offset
+MCA_SOS_OFFSET.  You can get that value from mca_asm.h or calculate it
+as KERNEL_STACK_SIZE - sizeof(struct pt_regs) - sizeof(struct
+ia64_sal_os_state), with 16 byte alignment for all structures.
+
+Also the comm field of the MCA/INIT task is modified to include the pid
+of the original task, for humans to use.  For example, a comm field of
+'MCA 12159' means that pid 12159 was running when the MCA was
+delivered.
diff --git a/Documentation/arch/ia64/serial.rst b/Documentation/arch/ia64/serial.rst
new file mode 100644
index 00000000000000..1de70c305a7911
--- /dev/null
+++ b/Documentation/arch/ia64/serial.rst
@@ -0,0 +1,165 @@
+==============
+Serial Devices
+==============
+
+Serial Device Naming
+====================
+
+    As of 2.6.10, serial devices on ia64 are named based on the
+    order of ACPI and PCI enumeration.  The first device in the
+    ACPI namespace (if any) becomes /dev/ttyS0, the second becomes
+    /dev/ttyS1, etc., and PCI devices are named sequentially
+    starting after the ACPI devices.
+
+    Prior to 2.6.10, there were confusing exceptions to this:
+
+	- Firmware on some machines (mostly from HP) provides an HCDP
+	  table[1] that tells the kernel about devices that can be used
+	  as a serial console.  If the user specified "console=ttyS0"
+	  or the EFI ConOut path contained only UART devices, the
+	  kernel registered the device described by the HCDP as
+	  /dev/ttyS0.
+
+	- If there was no HCDP, we assumed there were UARTs at the
+	  legacy COM port addresses (I/O ports 0x3f8 and 0x2f8), so
+	  the kernel registered those as /dev/ttyS0 and /dev/ttyS1.
+
+    Any additional ACPI or PCI devices were registered sequentially
+    after /dev/ttyS0 as they were discovered.
+
+    With an HCDP, device names changed depending on EFI configuration
+    and "console=" arguments.  Without an HCDP, device names didn't
+    change, but we registered devices that might not really exist.
+
+    For example, an HP rx1600 with a single built-in serial port
+    (described in the ACPI namespace) plus an MP[2] (a PCI device) has
+    these ports:
+
+      ==========  ==========     ============    ============   =======
+      Type        MMIO           pre-2.6.10      pre-2.6.10     2.6.10+
+		  address
+				 (EFI console    (EFI console
+                                 on builtin)     on MP port)
+      ==========  ==========     ============    ============   =======
+      builtin     0xff5e0000        ttyS0           ttyS1         ttyS0
+      MP UPS      0xf8031000        ttyS1           ttyS2         ttyS1
+      MP Console  0xf8030000        ttyS2           ttyS0         ttyS2
+      MP 2        0xf8030010        ttyS3           ttyS3         ttyS3
+      MP 3        0xf8030038        ttyS4           ttyS4         ttyS4
+      ==========  ==========     ============    ============   =======
+
+Console Selection
+=================
+
+    EFI knows what your console devices are, but it doesn't tell the
+    kernel quite enough to actually locate them.  The DIG64 HCDP
+    table[1] does tell the kernel where potential serial console
+    devices are, but not all firmware supplies it.  Also, EFI supports
+    multiple simultaneous consoles and doesn't tell the kernel which
+    should be the "primary" one.
+
+    So how do you tell Linux which console device to use?
+
+	- If your firmware supplies the HCDP, it is simplest to
+	  configure EFI with a single device (either a UART or a VGA
+	  card) as the console.  Then you don't need to tell Linux
+	  anything; the kernel will automatically use the EFI console.
+
+	  (This works only in 2.6.6 or later; prior to that you had
+	  to specify "console=ttyS0" to get a serial console.)
+
+	- Without an HCDP, Linux defaults to a VGA console unless you
+	  specify a "console=" argument.
+
+    NOTE: Don't assume that a serial console device will be /dev/ttyS0.
+    It might be ttyS1, ttyS2, etc.  Make sure you have the appropriate
+    entries in /etc/inittab (for getty) and /etc/securetty (to allow
+    root login).
+
+Early Serial Console
+====================
+
+    The kernel can't start using a serial console until it knows where
+    the device lives.  Normally this happens when the driver enumerates
+    all the serial devices, which can happen a minute or more after the
+    kernel starts booting.
+
+    2.6.10 and later kernels have an "early uart" driver that works
+    very early in the boot process.  The kernel will automatically use
+    this if the user supplies an argument like "console=uart,io,0x3f8",
+    or if the EFI console path contains only a UART device and the
+    firmware supplies an HCDP.
+
+Troubleshooting Serial Console Problems
+=======================================
+
+    No kernel output after elilo prints "Uncompressing Linux... done":
+
+	- You specified "console=ttyS0" but Linux changed the device
+	  to which ttyS0 refers.  Configure exactly one EFI console
+	  device[3] and remove the "console=" option.
+
+	- The EFI console path contains both a VGA device and a UART.
+	  EFI and elilo use both, but Linux defaults to VGA.  Remove
+	  the VGA device from the EFI console path[3].
+
+	- Multiple UARTs selected as EFI console devices.  EFI and
+	  elilo use all selected devices, but Linux uses only one.
+	  Make sure only one UART is selected in the EFI console
+	  path[3].
+
+	- You're connected to an HP MP port[2] but have a non-MP UART
+	  selected as EFI console device.  EFI uses the MP as a
+	  console device even when it isn't explicitly selected.
+	  Either move the console cable to the non-MP UART, or change
+	  the EFI console path[3] to the MP UART.
+
+    Long pause (60+ seconds) between "Uncompressing Linux... done" and
+    start of kernel output:
+
+	- No early console because you used "console=ttyS<n>".  Remove
+	  the "console=" option if your firmware supplies an HCDP.
+
+	- If you don't have an HCDP, the kernel doesn't know where
+	  your console lives until the driver discovers serial
+	  devices.  Use "console=uart,io,0x3f8" (or appropriate
+	  address for your machine).
+
+    Kernel and init script output works fine, but no "login:" prompt:
+
+	- Add getty entry to /etc/inittab for console tty.  Look for
+	  the "Adding console on ttyS<n>" message that tells you which
+	  device is the console.
+
+    "login:" prompt, but can't login as root:
+
+	- Add entry to /etc/securetty for console tty.
+
+    No ACPI serial devices found in 2.6.17 or later:
+
+	- Turn on CONFIG_PNP and CONFIG_PNPACPI.  Prior to 2.6.17, ACPI
+	  serial devices were discovered by 8250_acpi.  In 2.6.17,
+	  8250_acpi was replaced by the combination of 8250_pnp and
+	  CONFIG_PNPACPI.
+
+
+
+[1]
+    http://www.dig64.org/specifications/agreement
+    The table was originally defined as the "HCDP" for "Headless
+    Console/Debug Port."  The current version is the "PCDP" for
+    "Primary Console and Debug Port Devices."
+
+[2]
+    The HP MP (management processor) is a PCI device that provides
+    several UARTs.  One of the UARTs is often used as a console; the
+    EFI Boot Manager identifies it as "Acpi(HWP0002,700)/Pci(...)/Uart".
+    The external connection is usually a 25-pin connector, and a
+    special dongle converts that to three 9-pin connectors, one of
+    which is labelled "Console."
+
+[3]
+    EFI console devices are configured using the EFI Boot Manager
+    "Boot option maintenance" menu.  You may have to interrupt the
+    boot sequence to use this menu, and you will have to reset the
+    box after changing console configuration.
diff --git a/Documentation/arch/index.rst b/Documentation/arch/index.rst
index 2aeff47a00141e..77e287c3eeb9b7 100644
--- a/Documentation/arch/index.rst
+++ b/Documentation/arch/index.rst
@@ -12,7 +12,7 @@ implementation.
    arc/index
    ../arm/index
    ../arm64/index
-   ../ia64/index
+   ia64/index
    ../loongarch/index
    ../m68k/index
    ../mips/index