[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] xen EFI boot and vga-passthrough
> -----Original Message----- > From: Laszlo Ersek [mailto:lersek@xxxxxxxxxx] > On 11/12/12 20:08, Kristian Hagsted Rasmussen wrote: > > Hi all > > > > I can't seem to find any information on vga-passthrough when booting > > through xen.efi, so I assume it should work. But I encounter a problem > > on a windows 7 HVM that boots fine when dom0 is booted through MBR > but > > fails when dom0 is booted through UEFI. > > > > My system is: > > DQ77KB motherboard with bios version 44 Core i7-3779T with VT-d Intel > > HD graphics 4000 > > > > In the qemu log it seem like xen cannot reach the vga-bios. Is this a > > known problem when booting through xen.efi or is it a bug? > > The legacy VGA BIOS is not present on UEFI platforms unless an > (optional) compatibility support module provides it. (Tangentially, Secure > Boot disables CSMs.) > > Windows 7 / Windows 2008 R2 have a bug: even when booted on an UEFI > platform, they depend on the optional VGA BIOS unconditionally. This seems > to have been fixed in Windows 8 / Windows Server 2012. I will have to try to install windows 8 when I have time then. Just compared a log file from efi boot to one from MBR boot and found this discrepancy between the two: pt_register_regions: IO region registered (size=0x00400000 base_addr=0xdfc00004) - MBR boot see last addr 0xdfc00004 pt_register_regions: IO region registered (size=0x00400000 base_addr=0xf7000004) - EFI boot compare to MBR 0xf7000004 Can UEFI explain this discrepancy in base_addr? It is admittedly the first portion of memory on the graphic card and is 4M in size, so I suspect it is the vga-bios. And if it should not be present when boot through UEFI I will happily live with the error, if windows 8 can boot. > See <http://www.linux- > kvm.org/page/OVMF#Windows_Server_2008_R2_SP1> > and/or the long "OVMF + Windows 2008 r2 sp1" thread on edk2-devel. > > (Apologies if I misunderstood your question. Admittedly, I haven't done any > homework wrt. xen.efi or vga passthrough. But your email had too many > keywords to push my buttons.) > > Laszlo _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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