Xtensa processors are 32-bit RISC machines designed by Tensilica primarily for embedded systems. These processors are both configurable and extensible. The Linux port to the Xtensa architecture supports all processor configurations and extensions, with reasonable minimum requirements. The Xtensa Linux project has a home page at <http://xtensa.sourceforge.net/>.
This variant refers to Tensilica's Diamond 232L Standard core Rev.B (LE).
The Xtensa architecture currently does not handle unaligned memory accesses in hardware but through an exception handler. Per default, unaligned memory accesses are disabled in user space. Say Y here to enable unaligned memory access in user space.
This option reduces the latency of the kernel when reacting to real-time or interactive events by allowing a low priority process to be preempted even if it is in kernel mode executing a system call. Unfortunately the kernel code has some race conditions if both CONFIG_SMP and CONFIG_PREEMPT are enabled, so this option is currently disabled if you are building an SMP kernel. Say Y here if you are building a kernel for a desktop, embedded or real-time system. Say N if you are unsure.
Can we use information of configuration file?
On some platforms (XT2000, for example), the CPU clock rate can vary. The frequency can be determined, however, by measuring against a well known, fixed frequency, such as an UART oscillator.
Find out whether you have a PCI motherboard. PCI is the name of a bus system, i.e. the way the CPU talks to the other stuff inside your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or VESA. If you have PCI, say Y, otherwise N.
ISS is an acronym for Tensilica's Instruction Set Simulator.
XT2000 is the name of Tensilica's feature-rich emulation platform. This hardware is capable of running a full Linux distribution.
The BogoMIPS value can easily be derived from the CPU frequency.
On some architectures (EBSA110 and CATS), there is currently no way for the boot loader to pass arguments to the kernel. For these architectures, you should supply some command-line options at build time by entering them here. As a minimum, you should specify the memory size and the root device (e.g., mem=64M root=/dev/nfs).
Say Y here if you want to plug devices into your computer while the system is running, and be able to use them quickly. In many cases, the devices can likewise be unplugged at any time too. One well known example of this is PCMCIA- or PC-cards, credit-card size devices such as network cards, modems or hard drives which are plugged into slots found on all modern laptop computers. Another example, used on modern desktops as well as laptops, is USB. Enable HOTPLUG and build a modular kernel. Get agent software (from <http://linux-hotplug.sourceforge.net/>) and install it. Then your kernel will automatically call out to a user mode "policy agent" (/sbin/hotplug) to load modules and set up software needed to use devices as you hotplug them.
If you enabled support for /proc file system then the file /proc/kcore will contain the kernel core image in ELF format. This can be used in gdb: $ cd /usr/src/linux ; gdb vmlinux /proc/kcore This is especially useful if you have compiled the kernel with the "-g" option to preserve debugging information. It is mainly used for examining kernel data structures on the live kernel.
This is the filename of the ramdisk image to be built into the kernel. Relative pathnames are relative to arch/xtensa/boot/ramdisk/. The ramdisk image is not part of the kernel distribution; you must provide one yourself.