lkml.org 
[lkml]   [1998]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: SMP speed on 6x86 UP
    On Fri, 20 Mar 1998, MOLNAR Ingo wrote:

    > On Fri, 20 Mar 1998, Kurt Garloff wrote:
    >
    > > The 6x86 is configured using the processor ports 0x22 and 0x23. Mike Jagdis
    > > told me, that the APIC on Intels do use these registers. So, I consider this
    > > to be the most probable candidate for the problem.
    >
    > yep, if the BIOS lets us so far, this explains things. Could you try
    > removing the setup_IO_APIC(); line from smp.c? Does this fix the problem?

    A quick look at arch/i386/kernel/smp.c suggests that if an MP
    table exists at all we will make some writes to low I/O space
    (some would definitely clobber a 6x86 too but I haven't followed
    the code paths that closely).

    The implication is that motherboard manufacturers are perhaps
    standardizing the BIOS' they are shipping and non-SMP boards
    are advertising a single CPU MP table.

    My quick suggestion would be to change the "if (!smp_found_config)"
    test in smp_boot_cpus() to test the processor make as well and
    fail anything that isn't Intel.

    N.B. It took me longer to write this message than I spent looking
    at the code - that's all the time I get for lunch :-).

    Mike

    --
    .----------------------------------------------------------------------.
    | Mike Jagdis | Internet: mailto:mike@roan.co.uk |
    | Roan Technology Ltd. | |
    | 54A Peach Street, Wokingham | Telephone: +44 118 989 0403 |
    | RG40 1XG, ENGLAND | Fax: +44 118 989 1195 |
    `----------------------------------------------------------------------'


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu

    \
     
     \ /
      Last update: 2005-03-22 13:41    [W:0.021 / U:0.596 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site