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| author | Rafał Bilski <rafalbilski@interia.pl> | 2006-07-04 17:50:57 +0200 |
|---|---|---|
| committer | Dave Jones <davej@redhat.com> | 2006-07-31 18:37:05 -0400 |
| commit | 48b7bde0f6d5fd08d046b583cfa0118ad74c6caf (patch) | |
| tree | 67473b4acac35e23c6acfa17e7e5e4de3b626d15 /arch | |
| parent | dadb49d8746bc4a4b5a310dabf0c838e57a9b531 (diff) | |
| download | linux-48b7bde0f6d5fd08d046b583cfa0118ad74c6caf.tar.gz | |
[CPUFREQ] Longhaul - Workaround issues with APIC.
There is no need to worry about local APIC.
There is need to worry about I/O APIC, because I/O APIC
is replacing good old 8259. According to Nehemiah datasheet VIA is
using 3-wire bus to connect local APIC to I/O APIC.
"[...] When IA32_APIC_BASE[11] is set to 0, processor APICs based on the 3-wire APIC
bus cannot be generally re-enabled until a system hardware reset. The 3-wire bus
looses track of arbitration that would be necessary for complete re-enabling. Certain
(local) APIC functionality can be enabled. [...]"
So we must set disable bit for each interrupt in I/O APIC registers.
Same situation as for PIC - we must poke registers direcly.
How to do this? I don't know. So at the moment it is better to fail.
Signed-off-by: Rafał Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/i386/kernel/cpu/cpufreq/longhaul.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c index d735cb460612a9..dfd243f497b2da 100644 --- a/arch/i386/kernel/cpu/cpufreq/longhaul.c +++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c @@ -688,6 +688,18 @@ static int __init longhaul_init(void) if (c->x86_vendor != X86_VENDOR_CENTAUR || c->x86 != 6) return -ENODEV; +#ifdef CONFIG_SMP + if (num_online_cpus() > 1) { + return -ENODEV; + printk(KERN_ERR PFX "More than 1 CPU detected, longhaul disabled.\n"); + } +#endif +#ifdef CONFIG_X86_IO_APIC + if (cpu_has_apic) { + printk(KERN_ERR PFX "APIC detected. Longhaul is currently broken in this configuration.\n"); + return -ENODEV; + } +#endif switch (c->x86_model) { case 6 ... 9: return cpufreq_register_driver(&longhaul_driver); |