On Tue, 1 Jul 2008 01:11:35 +0100 (BST) Maciej W. Rozycki wrote:
> As discovered recently some systems exhibit problems when the 8254 timer
> IRQ is routed through the I/O APIC. These problems do not affect the
> timer IRQ itself and therefore cannot be detected when the correctness of
> operation of the interrupt is verified in check_timer(). Therefore the
> I/O APIC path of the timer IRQ has to be disabled entirely.
>
> This is a change that lets platforms ask for the timer IRQ not to be
> registered in the I/O APIC interrupt tables. The local APIC and ExtINTA
> paths are unaffected. This request is only taken into account for ACPI
> platforms as MP table systems seem unaffected so far.
>
> Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
> ---
> patch-2.6.26-rc1-20080505-mpparse-acpi-noirq0-2
> diff -up --recursive --new-file linux-2.6.26-rc1-20080505.macro/arch/x86/kernel/mpparse.c linux-2.6.26-rc1-20080505/arch/x86/kernel/mpparse.c
> --- linux-2.6.26-rc1-20080505.macro/arch/x86/kernel/mpparse.c 2008-05-05 02:56:19.000000000 +0000
> +++ linux-2.6.26-rc1-20080505/arch/x86/kernel/mpparse.c 2008-06-30 21:53:33.000000000 +0000
> @@ -50,6 +50,8 @@ static int mp_current_pci_id;
>
> int pic_mode;
>
> +int disable_irq0_through_ioapic __initdata;
> +
> /*
> * Intel MP BIOS table parsing routines:
> */
> @@ -887,6 +889,10 @@ void __init mp_override_legacy_irq(u8 bu
> int ioapic = -1;
> int pin = -1;
>
> + /* Skip the 8254 timer interrupt (IRQ 0) if requested. */
> + if (bus_irq == 0 && disable_irq0_through_ioapic)
> + return;
> +
> /*
> * Convert 'gsi' to 'ioapic.pin'.
> */
> @@ -955,6 +961,10 @@ void __init mp_config_acpi_legacy_irqs(v
> for (i = 0; i < 16; i++) {
> int idx;
>
> + /* Skip the 8254 timer interrupt (IRQ 0) if requested. */
> + if (i == 0 && disable_irq0_through_ioapic)
> + continue;
> +
> for (idx = 0; idx < mp_irq_entries; idx++) {
> struct mpc_config_intsrc *irq = mp_irqs + idx;
>
> diff -up --recursive --new-file linux-2.6.26-rc1-20080505.macro/include/asm-x86/mpspec.h linux-2.6.26-rc1-20080505/include/asm-x86/mpspec.h
> --- linux-2.6.26-rc1-20080505.macro/include/asm-x86/mpspec.h 2008-05-05 02:55:57.000000000 +0000
> +++ linux-2.6.26-rc1-20080505/include/asm-x86/mpspec.h 2008-06-30 22:29:23.000000000 +0000
> @@ -113,4 +113,15 @@ typedef struct physid_mask physid_mask_t
>
> extern physid_mask_t phys_cpu_present_map;
>
> +#ifdef CONFIG_X86_MPPARSE
> +static inline void set_disable_irq0_through_ioapic(int v)
> +{
> + extern int disable_irq0_through_ioapic;
> +
> + disable_irq0_through_ioapic = v;
> +}
> +#else
> +static inline void set_disable_irq0_through_ioapic(int v) { }
> +#endif
> +
> #endif
What calls set_disable_irq0_through_ioapic() ?
---
~Randy
Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA
http://linuxplumbersconf.org/
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
