Re: UP local APIC is deadly on SMP Athlon

From: Marc-Christian Petersen (m.c.p@wolk-project.de)
Date: Fri Feb 21 2003 - 16:41:23 EST


On Friday 21 February 2003 21:42, Ion Badulescu wrote:

Hi Ion,

> And this is what I found: eliminating two lines from
> APIC_init_uniprocessor() makes the problem go away.
> diff -urNX diff_kernel_excludes linux-2.4.10-pre12/arch/i386/kernel/apic.c
> linux-2.4.10-pre11++/arch/i386/kernel/apic.c ---
> linux-2.4.10-pre12/arch/i386/kernel/apic.c Wed Feb 19 23:53:15 2003 +++
> linux-2.4.10-pre11++/arch/i386/kernel/apic.c Fri Feb 21 15:37:06 2003 @@
> -1087,9 +1087,6 @@
>
> connect_bsp_APIC();
>
> - phys_cpu_present_map = 1;
> - apic_write_around(APIC_ID, boot_cpu_id);
> -
> apic_pm_init2();
>
> setup_local_APIC();
>
> [patch against 2.4.10-pre12, but 2.4.21-pre4 is reasonably similar]
Don't do this. I am pretty sure it will break all Intels. I still cannot
understand why this fixes your AMD Athlon problem.

ciao, Marc
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