Re: [RFC][PATCH] linux-2.5.69_clear-smi-fix_A0

[James Cleverdon <jamesclv@us.ibm.com>]

John,

That looks reasonable to me.  The one possible catch would be for systems so 
old they don't do SMI -- 386s and 486s, I imagine.  If this code doesn't barf 
on them when CONFIG_IO_APIC is turned on, then it should be fine (minus the 
printk).

(I believe there was at least one such system, the Intel Xpress box.  It 
contained a 486 and seperate APIC chips.)

		James

On Tuesday 06 May 2003 02:58 pm, john stultz wrote:
> All,
> 	I've been having problems with ACPI on a box here in our lab, it ends
> up that when we clear_IO_APIC() at boot time, we clear the SMI pin that
> is setup by the BIOS. This basically clobbers the SMI and we can then
> never make the transition into ACPI mode.
>
> I'm not sure if this is the right solution, but I figured I'd post it
> and take the flamage if I'm just being dumb. Basically in
> clear_IO_APIC_pin, I read the apic entry to make sure the delivery_mode
> isn't dest_SMI. If it is, we leave the apic entry alone and return.
>
> With this patch, the box boots and SMIs appear to function properly.
>
> Let me know if you have any thoughts or suggestions.
>
> thanks
> -john
>
>
> diff -Nru a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
> --- a/arch/i386/kernel/io_apic.c	Tue May  6 14:46:58 2003
> +++ b/arch/i386/kernel/io_apic.c	Tue May  6 14:46:58 2003
> @@ -219,6 +219,14 @@
>  {
>  	struct IO_APIC_route_entry entry;
>  	unsigned long flags;
> +
> +	/* Check delivery_mode to be sure we're not clearing an SMI pin */
> +	*(((int*)&entry) + 0) = io_apic_read(apic, 0x10 + 2 * pin);
> +	*(((int*)&entry) + 1) = io_apic_read(apic, 0x11 + 2 * pin);
> +	if (entry.delivery_mode == dest_SMI){
> +		printk(KERN_INFO "apic %i pin %i is an SMI pin!\n", apic, pin);
> +		return;
> +	}
>
>  	/*
>  	 * Disable it in the IO-APIC irq-routing table:

-- 
James Cleverdon
IBM xSeries Linux Solutions
{jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot com