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 driver implements the VIRTIO_DEVICE_PROTOCOL for non-transitional PCI
devices, based on the virtio-1.0 specification (csprd05). Non-transitional
means that it only binds QEMU's virtio-xxx-pci devices that receive the
",disable-legacy=on,disable-modern=off" properties on the QEMU command
line. These devices have distinct PCI Device IDs from those that are bound
by VirtioPciDeviceDxe.
The central abstraction of this driver is the VIRTIO_1_0_CONFIG type. It
is practically a "fat pointer" to a register block. The pointed-to
register block
- may or may not exist (the latter being mostly useful for virtio-1.0
devices that have no device-specific registers),
- lives in one of the device's BARs,
- lives in an IO or MMIO BAR,
- lives at an offset relative to the BAR start,
- has its size also maintained.
Such VIRTIO_1_0_CONFIG "fat pointers" (i.e., the locations of the register
blocks) are parsed from vendor capabilities that reside in the device's
standard PCI capabilities list (in PCI config space).
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Laszlo Ersek