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706b5b6277
Most of QEMU's PCI display device models, such as: libvirt video/model/@type QEMU -device ------------------------- ------------ cirrus cirrus-vga vga VGA qxl qxl-vga virtio virtio-vga come with a linear framebuffer (sometimes called "VGA compatibility framebuffer"). This linear framebuffer lives in one of the PCI device's MMIO BARs, and allows guest code (primarily: firmware drivers, and non-accelerated OS drivers) to display graphics with direct memory access. Due to architectural reasons on aarch64/KVM hosts, this kind of framebuffer doesn't / can't work in qemu-system-(arm|aarch64) -M virt machines. Cache coherency issues guarantee a corrupted / unusable display. The problem has been researched by several people, including kvm-arm maintainers, and it's been decided that the best way (practically the only way) to have boot time graphics for such guests is to consolidate on QEMU's "virtio-gpu-pci" device. >From <https://bugzilla.redhat.com/show_bug.cgi?id=1195176>, libvirt supports <devices> <video> <model type='virtio'/> </video> </devices> but libvirt unconditionally maps @type='virtio' to QEMU's "virtio-vga" device model. (See the qemuBuildDeviceVideoStr() function and the "qemuDeviceVideo" enum impl.) According to the above, this is not right for the "virt" machine type; the qemu-system-(arm|aarch64) binaries don't even recognize the "virtio-vga" device model (justifiedly). Whereas "virtio-gpu-pci", which is a pure virtio device without a compatibility framebuffer, is available, and works fine. (The ArmVirtQemu ("AAVMF") platform of edk2 -- that is, the UEFI firmware for "virt" -- supports "virtio-gpu-pci", as of upstream commit 3ef3209d3028. See <https://tianocore.acgmultimedia.com/show_bug.cgi?id=66>.) Override the default mapping of "virtio", from "virtio-vga" to "virtio-gpu-pci", if qemuDomainMachineIsVirt() evaluates to true. Cc: Andrea Bolognani <abologna@redhat.com> Cc: Drew Jones <drjones@redhat.com> Cc: Marc-André Lureau <marcandre.lureau@redhat.com> Cc: Martin Kletzander <mkletzan@redhat.com> Suggested-by: Marc-André Lureau <marcandre.lureau@redhat.com> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1372901 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Acked-by: Martin Kletzander <mkletzan@redhat.com>
37 lines
1.3 KiB
XML
37 lines
1.3 KiB
XML
<domain type='qemu'>
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<name>aarch64-vgpu</name>
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<uuid>f3197c89-6457-44fe-b26d-897090ba6541</uuid>
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<memory unit='KiB'>1048576</memory>
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<currentMemory unit='KiB'>1048576</currentMemory>
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<vcpu placement='static'>1</vcpu>
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<os>
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<type arch='aarch64' machine='virt'>hvm</type>
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</os>
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<features>
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<acpi/>
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</features>
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<cpu mode='custom' match='exact'>
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<model fallback='allow'>cortex-a57</model>
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</cpu>
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<devices>
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<emulator>/opt/qemu-installed/bin/qemu-system-aarch64</emulator>
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<controller type='pci' index='0' model='pcie-root'/>
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<controller type='pci' index='1' model='pcie-root-port'>
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<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0' multifunction='on'/>
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</controller>
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<controller type='pci' index='2' model='pcie-root-port'>
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<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1' multifunction='on'/>
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</controller>
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<interface type='user'>
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<mac address='52:54:00:73:34:53'/>
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<model type='virtio'/>
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<boot order='1'/>
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<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
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</interface>
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<video>
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<model type='virtio'/>
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<address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
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</video>
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</devices>
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</domain>
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