Messages in this thread | | | Date | Sat, 22 Feb 2003 01:38:49 +0100 (MET) | From | Mikael Pettersson <> | Subject | Re: UP local APIC is deadly on SMP Athlon |
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On Fri, 21 Feb 2003 22:41:23 +0100, Marc-Christian Petersen wrote: >> 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.
This is interesting. Very interesting, even. A plain UP_APIC kernel (with IO_APIC not enabled or not detected) shouldn't need to touch APIC_ID at all. I strongly suspect this is a remnant of apic.c's old SMP-only history, and that it should be removed for UP_APIC-only.
I need to get some downtime (zzz...) but I'll look into this ASAP.
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