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    Subject[regression, bisected] fails to boot on Dell Optiplex 760 with VT-d enabled
    I am experiencin a bug on an Dell Optiplex 760 with a configuration that
    has an Intel Core2 Q9550 CPU and with an up-to-date BIOS, version A03.

    When "VT for Direct I/O" is enabled in the BIOS, v2.6.30 boots and works
    perfectly, while v2.6.31-rc1..rc6 fail (both of them x86-64).

    More specifically, I get an endless loop of printing the following
    messages in
    the screen:
    DMAR: [DMA Read] Request device [ff:1f.7] fault addr
    DMAR: [fault reason 255] Unknown
    and the boot process doesn't move on from there.

    I ran git bisect good v2.6.30/bad v2.6.31-rc1 and I was pointed to the
    following commit:
    x86, intr-remap: enable interrupt remapping early

    I have no idea if VT-d is functioning on v2.6.30; I just had the option
    enabled in the BIOS and noticed the problem when I tried to upgrade to

    I've read a similar bug report against a Mandriva kernel and another
    VT-d related bug for the same hardware against Xen and in both threads
    they were finger-pointing the BIOS.

    I'm not sure if that's the case but, even if it is, I'd expect the
    system to boot, like previous versions did, perhaps printing a warning
    about VT-d functionality.


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      Last update: 2009-08-18 00:07    [W:0.021 / U:2.628 seconds]
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