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    SubjectRe: [PATCH -v2 1/2] x86: Reserve [0xa0000, 0x100000] in e820 map
    On 04/13/2010 03:29 PM, Yinghai wrote:
    > On 04/13/2010 02:58 PM, H. Peter Anvin wrote:
    >> On 04/13/2010 02:42 PM, Yinghai wrote:
    >>> On 04/13/2010 02:18 PM, H. Peter Anvin wrote:
    >>>> On 04/13/2010 02:11 PM, Yinghai wrote:
    >>>>>> I guess the real question (which I haven't looked at myself) is if the
    >>>>>> E820_RESERVED -> BUSY will cause an explicitly assigned BAR from being
    >>>>>> moved. That's bad, not so much for this particular range, but from BARs
    >>>>>> which may be assigned by SMM. Hacking that up in a simulator
    >>>>>> (Qemu/Bochs) and testing it is probably on the to do list...
    >>>>> no, if some device BAR fall in that range, it should still use that range, and will not be relocated.
    >>>>> will update the change log.
    >>>> Good, that's what we want.
    >>> the driver for that device later can not use pci_request_region(). because that region is BUSY already.
    >> That's not good (in general - for devices in this particular range it's
    >> not such a big deal, but it is potentially really bad for devices marked
    >> reserved for them not to be moved.)
    >> We have talked about a need to resolve this before.
    > current code for mmio that is just below 4g, if some PCI BAR use that range, and those range is falling into E820_RESERVED,
    > those range still can be claimed, but driver can not use pci_request_region() later.
    should be
    but driver can use pci_request_region() later.

    > So We still
    > 1. rely that BIOS does not reserve the [0xa0000, 0xe0000)
    > 2. kernel only reserve the range when we make sure these is legacy device on that range.
    > YH

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