On 2014/6/24 10:59, Zhenyu Wang wrote: > On 2014.06.19 17:53:51 +0800, Tiejun Chen wrote: >> Originally the reason to probe ISA bridge instead of Dev31:Fun0 >> is to make graphics device passthrough work easy for VMM, that >> only need to expose ISA bridge to let driver know the real >> hardware underneath. This is a requirement from virtualization >> team. Especially in that virtualized environments, XEN, there >> is irrelevant ISA bridge in the system with that legacy qemu >> version specific to xen, qemu-xen-traditional. So to work >> reliably, we should scan through all the ISA bridge devices >> and check for the first match, instead of only checking the >> first one. >> >> But actually, qemu-xen-traditional, is always enumerated with >> Dev31:Fun0, 00:1f.0 as follows: >> >> hw/pt-graphics.c: >> >> intel_pch_init() >> | >> + pci_isa_bridge_init(bus, PCI_DEVFN(0x1f, 0), ...); >> >> so this mean that isa bridge is still represented with Dev31:Func0 >> like the native OS. Furthermore, currently we're pushing VGA >> passthrough support into qemu upstream, and with some discussion, >> we wouldn't set the bridge class type and just expose this devfn. >> >> So we just go back to check devfn to make life normal. >> >> Signed-off-by: Tiejun Chen <tiejun.chen at intel.com> > > This was added historically when supporting graphics device passthrough. > Looks qemu upstream can't accept multiple ISA bridge and our PCH is always > on device 31: func0 as far as I know. Looks good to me. > > Reviewed-by: Zhenyu Wang <zhenyuw at linux.intel.com> >
Thanks for your review. Do you know when this can be applied? Tiejun
