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    SubjectRe: [PATCH] x86/pci: intel ioh need to subtract mmconf range
    On 01/14/2010 03:09 PM, Bjorn Helgaas wrote:
    > On Thursday 14 January 2010 03:46:35 pm Yinghai Lu wrote:
    >>
    >> Bjorn pointed out we need to remove mmconf range
    >>
    >> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
    >>
    >> ---
    >> arch/x86/pci/intel_bus.c | 29 +++++++++++++++++++++++++++--
    >> 1 file changed, 27 insertions(+), 2 deletions(-)
    >>
    >> Index: linux-2.6/arch/x86/pci/intel_bus.c
    >> ===================================================================
    >> --- linux-2.6.orig/arch/x86/pci/intel_bus.c
    >> +++ linux-2.6/arch/x86/pci/intel_bus.c
    >> @@ -46,6 +46,20 @@ static inline void print_ioh_resources(s
    >>
    >> #define RANGE_NUM 16
    >>
    >> +static void __devinit subtract_mmconf(struct range *range, int nr)
    >> +{
    >> +#ifdef CONFIG_PCI_MMCONFIG
    >> + struct pci_mmcfg_region *cfg;
    >> +
    >> + if (list_empty(&pci_mmcfg_list))
    >> + return;
    >> +
    >> + list_for_each_entry(cfg, &pci_mmcfg_list, list)
    >> + subtract_range(range, nr, cfg->res.start,
    >> + cfg->res.end + 1);
    >> +#endif
    >
    > This can't be right, can it? Let's say the kernel was built with
    > CONFIG_PCI_MMCONFIG turned off, or the user used "pci=nommconf",
    > or the kernel decides not to use MMCONFIG for some other reason.
    >
    > In that case, the hardware may still be configured to support
    > MMCONFIG, but the pci_mmcfg_list will be empty, so your code will
    > leave the window alone. We might assign some of that MMCONFIG
    > space to a device, but the hardware will route it to MMCONFIG,
    > not to the device.

    so if there is mmconf specified, we just skip the whole function?

    YH


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