lkml.org 
[lkml]   [2001]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: BUG: Global FPU corruption in 2.2
    On Tue, Apr 24, 2001 at 08:05:15AM -0500, Victor Zandy wrote:
    >
    > He found that PF_USEDFPU was always set before the machine was broken.
    > After he found that it was set about 70% of the time.

    If I'm not mistaken this actully can cause GLOBAL FPU corruption.
    Here's why:

    Assyme for a moment that we lose either the PF_USEDFPU flag of one
    process. This not only means that the current process won't have its
    state saved, it also means that the next process won't have the TS bit
    set. This in turn means that this new process won't get PF_USEDFPU set
    and suddenly we have a second process with a corrupted FPU state.

    Victor: Could you try to reproduce the system wide corruption if you
    add an explicit call to stts(); at the very end of __switch_to?
    This should prevent the FPU corruption from spreading.

    NOTE: This is just to prove my theory, it is not and isn't meant
    to be a fix for the actual problem.

    regards Christian Ehrhardt

    --

    THAT'S ALL FOLKS!
    -
    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: 2005-03-22 13:17    [W:0.020 / U:0.288 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site