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    SubjectRe: [PATCH 0/5] i387: stable kernel backport
    On Thu, Feb 23, 2012 at 1:52 PM, Willy Tarreau <w@1wt.eu> wrote:
    >
    > I would test this too, but apart from ensuring my kernel still boots,
    > how do I ensure the patches do really fix what the ought to fix ? I
    > must admit I didn't catch the initial issue they were supposed to fix
    > unfortunately :-/

    Almost nobody did.

    This only happens on modern CPU's that support the new AES-NI
    instructions, and only with a 32-bit kernel (although the very
    unlikely preemption issues can happen on x86-64 too). And you need to
    have the AES instructions called from interrupts, which probably only
    happens with the mac80211 wireless networking stack.

    And even then you need WPA2 to trigger it (I guess AES is sometimes
    used with "extended WPA1" too, but I dunno).

    So it's not impossible to trigger, but you do need to have a fairly
    recent CPU that happily runs in 64-bit mode, and install a 32-bit
    system on it. And it needs to use the right wireless setup.

    It's possible that the right solution for really older kernels is just
    to say that AES_NI depends on X86_64.

    Linus


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