On 08/22/17 18:30, Ard Biesheuvel wrote: > One of the reasons for introducing virtio-gpu support to OvmfPkg and > ArmVirtpkg was the fact that under KVM virtualization on ARM, the > legacy VGA cannot be used reliably. This is due to an implementation > detail of QEMU+KVM, which remaps cached host memory into the guest > address space as a framebuffer behind a PCI BAR. Given that the purpose > of a memory mapped framebuffer is its side effects, such BARs should > never be mapped cacheable in the guest, and the mismatched attributes > between host and guest result in a loss of coherency, visible as > corruption in the framebuffer image. > > This issue does not occur under TCG emulation, nor did we expect it to > actually bring down the guest under KVM, and so it was deemed harmless > to keep support for the VGA device as well. However, as it turns out, > the fact that the framebuffer BAR is mapped using device semantics by > default may result in unalignment faults when we use the ordinary string > copy routines on the contents. In theory, we could work around this by > remapping the BAR as write combining, but it appears the generic PCI > bus driver does not actually implement this. > > So let's remove the QemuVideoDxe driver altogether. This may result > in loss of functionality for use cases that rely on the framebuffer > to be directly addressable (such as EFIFB), but given that this never > worked reliably under KVM in the first place, let's not let that stop > us from dropping support for it. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <[email protected]> > --- > ArmVirtPkg/ArmVirtQemu.dsc | 2 -- > ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc | 1 - > ArmVirtPkg/ArmVirtQemuKernel.dsc | 2 -- > 3 files changed, 5 deletions(-) > > diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc > index e23a6d17bc44..2e6e76224987 100644 > --- a/ArmVirtPkg/ArmVirtQemu.dsc > +++ b/ArmVirtPkg/ArmVirtQemu.dsc > @@ -57,7 +57,6 @@ > BootLogoLib|MdeModulePkg/Library/BootLogoLib/BootLogoLib.inf > > PlatformBootManagerLib|ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf > > CustomizedDisplayLib|MdeModulePkg/Library/CustomizedDisplayLib/CustomizedDisplayLib.inf > - > FrameBufferBltLib|MdeModulePkg/Library/FrameBufferBltLib/FrameBufferBltLib.inf > QemuBootOrderLib|OvmfPkg/Library/QemuBootOrderLib/QemuBootOrderLib.inf > FileExplorerLib|MdeModulePkg/Library/FileExplorerLib/FileExplorerLib.inf > > PciPcdProducerLib|ArmVirtPkg/Library/FdtPciPcdProducerLib/FdtPciPcdProducerLib.inf > @@ -357,7 +356,6 @@ > # > # Video support > # > - OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf > OvmfPkg/VirtioGpuDxe/VirtioGpu.inf > OvmfPkg/PlatformDxe/Platform.inf > > diff --git a/ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc > b/ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc > index 237b2d03a714..3194aa3edc8e 100644 > --- a/ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc > +++ b/ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc > @@ -167,7 +167,6 @@ READ_LOCK_STATUS = TRUE > # > # Video support > # > - INF OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf > INF OvmfPkg/VirtioGpuDxe/VirtioGpu.inf > INF OvmfPkg/PlatformDxe/Platform.inf > > diff --git a/ArmVirtPkg/ArmVirtQemuKernel.dsc > b/ArmVirtPkg/ArmVirtQemuKernel.dsc > index aa01debfda69..69de887277cb 100644 > --- a/ArmVirtPkg/ArmVirtQemuKernel.dsc > +++ b/ArmVirtPkg/ArmVirtQemuKernel.dsc > @@ -57,7 +57,6 @@ > BootLogoLib|MdeModulePkg/Library/BootLogoLib/BootLogoLib.inf > > PlatformBootManagerLib|ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf > > CustomizedDisplayLib|MdeModulePkg/Library/CustomizedDisplayLib/CustomizedDisplayLib.inf > - > FrameBufferBltLib|MdeModulePkg/Library/FrameBufferBltLib/FrameBufferBltLib.inf > QemuBootOrderLib|OvmfPkg/Library/QemuBootOrderLib/QemuBootOrderLib.inf > FileExplorerLib|MdeModulePkg/Library/FileExplorerLib/FileExplorerLib.inf > > PciPcdProducerLib|ArmVirtPkg/Library/FdtPciPcdProducerLib/FdtPciPcdProducerLib.inf > @@ -348,7 +347,6 @@ > # > # Video support > # > - OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf > OvmfPkg/VirtioGpuDxe/VirtioGpu.inf > OvmfPkg/PlatformDxe/Platform.inf > >
Reviewed-by: Laszlo Ersek <[email protected]> Thanks! Laszlo _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
