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    SubjectRe: 256 apic id for amd64
    YhLu <> writes:

    > Can someone who maintains the x86-64 io_apic.c look at my patch about 256
    > apic id for amd64?

    First in general if you want patches submitted look up the maintainer
    in the MAINTAINERS file in the source tree and send it directly
    to the appropiate person and mailing list.

    Just curious - how many IO-APICs does your system have?

    Then I don't like your patch very much, since it doesnt handle
    Intel systems. The best fix is probably to

    i386 also has a different (but Intel specific fix) - uses either
    0xf or 0xff based on the APIC version. Just dropping it seems
    better to me though. I suppose Matt (cc'ed) who apparently
    wrote this code originally used it to work around some BIOS
    bug, and at least we can hope for now that there are no
    EM64T boxes with that particular BIOS bug.

    I will add this patch.


    Remove check that limited max number of IO-APIC to 8.

    The original check was apparently to work around some old BIOS
    bugs and we just assume x86-64 machines don't have this class of

    Signed-off-by: Andi Kleen <>

    diff -u linux-2.6.10/arch/x86_64/kernel/io_apic.c-o linux-2.6.10/arch/x86_64/kernel/io_apic.c
    --- linux-2.6.10/arch/x86_64/kernel/io_apic.c-o 2004-12-24 22:34:45.000000000 +0100
    +++ linux-2.6.10/arch/x86_64/kernel/io_apic.c 2004-12-30 19:41:08.000000000 +0100
    @@ -1160,13 +1160,6 @@

    old_id = mp_ioapics[apic].mpc_apicid;

    - if (mp_ioapics[apic].mpc_apicid >= 0xf) {
    - apic_printk(APIC_QUIET,KERN_ERR "BIOS bug, IO-APIC#%d ID is %d in the MPC table!...\n",
    - apic, mp_ioapics[apic].mpc_apicid);
    - apic_printk(APIC_QUIET,KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
    - reg_00.bits.ID);
    - mp_ioapics[apic].mpc_apicid = reg_00.bits.ID;
    - }

    printk(KERN_INFO "Using IO-APIC %d\n", mp_ioapics[apic].mpc_apicid);

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      Last update: 2005-03-22 14:09    [W:0.030 / U:23.608 seconds]
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