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    SubjectRe: Patch "USB: Work around BIOS bugs by quiescing USB controllers earlier" causes MCEs
    Mikael Pettersson writes:
    > Nick Piggin writes:
    > > Hi,
    > >
    > > Your patch db8be50c4307dac2b37305fc59c8dc0f978d09ea is causing my
    > > ia64 Altix system to die with an MCE in early boot.
    >
    > The same commit has been confirmed by two people on the ARM list
    > to cause boot failures on two different Intel XScale IOP machines.
    > The machines have serial consoles, but only show
    >
    > Uncompressing Linux... done. Booting the kernel.
    >
    > before they hang.

    I've just investigated this on one of my ARM boxes that this commit kills.

    The commit changed quirk_usb_early_handoff to be a FIXUP_HEADER, which
    caused it to be invoked during the early stages of the platform's PCI
    init (arch/arm/kernel/bios32.c). quirk_usb_handoff_uhci() gets a bogus
    I/O base address, passes that down to uhci_reset_hc(), causing a kernel
    page fault in the first "outw(UHCI_USBCMD_HCRESET, base + UHCI_USBCMD);",
    causing the kernel to oops.

    (All this occurs before the serial console works, so I had to add a
    platform-specific puts() and lots of tracing statements.)

    Changing this quirk back to a FIXUP_FINAL allows the platform's PCI
    init to complete. Later on the generic pci_init() calls the quirk,
    which now gets the correct I/O base address, and the outw()s in
    uhci_reset_hc() don't fail.


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