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OvmfPkg/Virtio10Dxe: don't bind virtio-vga 

Commit 9399f68ae3 ("OvmfPkg: Virtio10Dxe: non-transitional driver for
virtio-1.0 PCI devices") created a "competition" between Virtio10Dxe and
QemuVideoDxe for virtio-vga devices. The binding order between these
drivers is unspecified, and the wrong order effectively breaks commit
94210dc95e ("OvmfPkg: QemuVideoDxe: add virtio-vga support").

Thus, never bind virtio-vga in Virtio10Dxe; QemuVideoDxe provides better
compatibility for guest OSes that insist on inheriting a linear
framebuffer. Users who prefer the VirtIo GPU interface at boot time should
specify virtio-gpu-pci, which is exactly virtio-vga, minus the VGA
compatibility (such as the framebuffer).

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://tianocore.acgmultimedia.com/show_bug.cgi?id=66
Fixes: 9399f68ae3
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
This commit is contained in:
Laszlo Ersek 2016-08-18 13:52:26 +02:00
parent 442c2ab81e
commit 76569ca855
1 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
OvmfPkg/Virtio10Dxe/Virtio10.c
View File

@ -822,6 +822,7 @@ Virtio10BindingSupported (
goto CloseProtocol;
}
Status = EFI_UNSUPPORTED;
//
// Recognize non-transitional modern devices. Also, we'll have to parse the
// PCI capability list, so make sure the CapabilityPtr field will be valid.
@ -832,9 +833,20 @@ Virtio10BindingSupported (
Pci.Hdr.RevisionID >= 0x01 &&
Pci.Device.SubsystemID >= 0x40 &&
(Pci.Hdr.Status & EFI_PCI_STATUS_CAPABILITY) != 0) {
Status = EFI_SUCCESS;
} else {
Status = EFI_UNSUPPORTED;
//
// The virtio-vga device is special. It can be driven both as a VGA device
// with a linear framebuffer, and through its underlying, modern,
// virtio-gpu-pci device, which has no linear framebuffer itself. For
// compatibility with guest OSes that insist on inheriting a linear
// framebuffer from the firmware, we should leave virtio-vga to
// QemuVideoDxe, and support only virtio-gpu-pci here.
//
// Both virtio-vga and virtio-gpu-pci have DeviceId 0x1050, but only the
// former has device class PCI_CLASS_DISPLAY_VGA.
//
if (Pci.Hdr.DeviceId != 0x1050 || !IS_PCI_VGA (&Pci)) {
Status = EFI_SUCCESS;
}
}
CloseProtocol: