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    SubjectRe: [PATCH RFC] x86: check for and defend against BIOS memory corruption
    Rafał Miłecki wrote:
    > 2008/8/29 Hugh Dickins <hugh@veritas.com>:
    >
    >>> On Fri, 29 Aug 2008, Rafał Miłecki wrote:
    >>>
    >>> Out of current discussion I tried using s2ram on patched kernel (I did
    >>> not try s2ram earlier, my problem was (un)plugging HDMI - some ACPI
    >>> code probably).
    >>>
    >>> Corruption output is quite huge, I attached it to bug report:
    >>> http://bugzilla.kernel.org/show_bug.cgi?id=11237
    >>> http://bugzilla.kernel.org/attachment.cgi?id=17526
    >>>
    >> Not quite the output we were expecting! I've not got around to trying
    >> it yet, so beware, but I think Jeremy's patch needs the following on top.
    >> Or you may prefer to wait until one of us reports that it is now working
    >> as intended.
    >>
    >> --- a/arch/x86/kernel/setup.c 2008-08-29 11:17:16.000000000 +0100
    >> +++ b/arch/x86/kernel/setup.c 2008-08-29 11:19:24.000000000 +0100
    >> @@ -636,11 +636,12 @@ void check_for_bios_corruption(void)
    >> unsigned long *addr = __va(scan_areas[i].addr);
    >> unsigned long size = scan_areas[i].size;
    >>
    >> - for(; size; addr++, size--) {
    >> + for(; size; addr++, size -= sizeof(unsigned long)) {
    >> if (!*addr)
    >> continue;
    >> printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
    >> addr, __pa(addr), *addr);
    >> + *addr = 0;
    >> corruption = 1;
    >> }
    >> }
    >>
    >
    > I tried your patch anyway (after applying Jeremy's patch of course)
    > and it doesn't seem to work. The only output is:
    > scanning 2 areas for BIOS corruption
    > after using s2ram. I do not get any
    > Corrupted low memory at*
    >
    It seemed to work for me. Did you remember to plug HDMI to trigger the
    corruption before you used s2ram?

    [ 71.663828] Back to C!
    [ 71.663828] Corrupted low memory at ffff8800000083e8 (83e8 phys) =
    803c85370cfc0000
    [ 71.663828] Corrupted low memory at ffff8800000083f0 (83f0 phys) =
    00003000
    [ 71.663828] Pid: 7335, comm: pm-suspend Not tainted
    2.6.27-rc4-00216-ge1c9c9d-dirty #152
    [ 71.663828]
    [ 71.663828] Call Trace:
    [ 71.663828] [<ffffffff8020fdd5>] check_for_bios_corruption+0xb5/0xd0
    [ 71.663828] [<ffffffff803a3e1a>] pm_dev_dbg+0x2a/0xa0
    [ 71.663828] [<ffffffff803a49c2>] dpm_power_up+0x32/0xf0

    Alan
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