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    SubjectRe: [RFC PATCH] PCI MMCONFIG: add validation against ACPI motherboard resources
    Date
    On Tuesday, May 22, 2007, Robert Hancock wrote:
    > Eww. I don't see where we disable the decode at all while we probe the
    > BARs on the device. That seems like a bad thing, especially with the way
    > we probe 64-bit BARs (do the low 32 bits first and then the high 32
    > bits). This means the base address effectively gets set to 0xfffffff0
    > momentarily, which might cause some issues.

    I'm a bit shocked that things work as well as they do without the
    disabling...

    > I'd try adding some code inside pci_setup_device (drivers/pci/probe.c)
    > to disable PCI_COMMAND_IO and PCI_COMMAND_MEMORY on the device when
    > probing devices with the standard header type and then restoring the
    > previous command bits afterwards, and see what effect that has. It'll be
    > interesting if it does, since obviously it seems to work as it is with
    > non-MMCONFIG access methods. Maybe the base address being set like that
    > interferes with MMCONFIG access itself somehow?

    I tried that, and it seems to get past probing the graphics device at
    least, but it hangs a bit later. It could be that the enable/disable I
    added wasn't correct though, I didn't check to see which one I should
    disable in the command word, which may be a problem (just disabled them
    both every probe). I'll try again with more precise enable/disable
    semantics.

    Jesse
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