lkml.org 
[lkml]   [2007]   [Jan]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    SubjectPATCH: Update disable_IO_APIC to use 8-bit destination field (X86_64)
    From
    Date
    On the Unisys ES7000/ONE system, we encountered a problem where
    performing a kexec reboot or dump on any cell other than cell 0 causes
    the system timer to stop working, resulting in a hang during timer
    calibration in the new kernel.

    We traced the problem to one line of code in disable_IO_APIC(), which
    needs to restore the timer's IO-APIC configuration before rebooting. The
    code is currently using the 4-bit physical destination field, rather
    than using the 8-bit logical destination field, and it cuts off the
    upper 4 bits of the timer's APIC ID. If we change this to use the
    logical destination field, the timer works and we can kexec on the upper
    cells. This was tested on two different cells (0 and 2) in an ES7000/ONE
    system.

    For reference, the relevant Intel xAPIC spec is kept at
    ftp://download.intel.com/design/chipsets/e8501/datashts/30962001.pdf,
    specifically on page 334.

    -- Ben

    --- linux-2.6.19.2.orig/arch/x86_64/kernel/io_apic.c 2007-01-10
    14:10:37.000000000 -0500
    +++ linux-2.6.19.2/arch/x86_64/kernel/io_apic.c 2007-01-17
    09:20:24.000000000 -0500
    @@ -1261,7 +1261,7 @@
    entry.dest_mode = 0; /* Physical */
    entry.delivery_mode = dest_ExtINT; /* ExtInt */
    entry.vector = 0;
    - entry.dest.physical.physical_dest =
    + entry.dest.logical.logical_dest =
    GET_APIC_ID(apic_read(APIC_ID));

    /*

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-01-17 19:09    [W:0.021 / U:0.440 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site