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Marcel ApfelbaumAugust, 2016
Q35 - QEMU
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Agenda
● Q35 chipset - Overview
● Q35 emulation
● Q35-only features
● Q35 limitations
● Q35 use cases
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Q35 chipset - Overview
● Data sheet
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Q35 chipset - Overview
● Topology
– North Bridge: MCH
– South Bridge: ICH9
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Agenda
● Q35 chipset - Overview
● Q35 emulation
● Q35-only features
● Q35 limitations
● Q35 use cases
![Page 6: Q35 - QEMU · 15 Q35 limitations No support for legacy guests (Windows XP/2000). Questionable support for legacy QEMU devices. Limited IO space can affect the number of devices used](https://reader035.vdocument.in/reader035/viewer/2022063001/5f12e547b1382150b801334e/html5/thumbnails/6.jpg)
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Q35 emulation
● Info qtree
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Q35 emulation
● lspci
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Q35 emulation
● PCIe/PCI Topology
Bus 0 Bus 0Q35 I440FX
Dev 1 Dev 2 P2P bridge
Bus 1
Dev 3P2P
bridge
Bus 2
DMI-PCI bridge
Bus 5
Dev 3P2P
bridgeBus 6
Root Port 1
Bus 1
PCIe Dev 2
PCIe Dev 3
Bus 4
Integrated PCIe Dev 1
Upstream Port 1
Bus 3
Downstream Port 1
Root Port 2 Bus 2
Switch
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Q35 emulation
● PCI/PCIe devices placement
Bus 0
Integrated PCI Dev 1
Root Port 1
Bus 1
PCIe Dev 2
PCIe Dev 3
Bus 4
DMI-PCI bridge
Bus 5
PCI Dev 2
P2P bridge
Bus 6
PCIe devices PCI devices
Integrated PCIe Dev 1
PCI Dev 3
Upstream Port 1
Bus 3
Downstream Port 1
Root Port 2 Bus 2
Switch
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Q35 emulation
● PCIe/PCI ACPI Hotplug
Bus 0
Integrated PCI Dev 1
Root Port 1
Bus 1
PCIe Dev 2
PCIe Dev 3
Bus 4
DMI-PCI bridge
Bus 5
PCI Dev 2
P2P bridge
Bus 6
PCIe native hotplug
Integrated PCIe Dev 1
PCI Dev 3 PCI ACPI hotplug
Upstream Port 1
Bus 3
Downstream Port 1
Root Port 2 Bus 2
Switch
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Q35 emulation
● Virtio
Bus 0
Integrated PCI Dev 1
PCIe Dev 3
Bus 4
DMI-PCI bridge
Bus 5
PCI Dev 2
P2P bridge
Bus 6
PCIe + Pure virtio 1.0 (disable-legacy=on,disable-modern=off)
PCI + Transitional virtio (disable-legacy=off,disable-modern=off)
PCI Dev 3
Upstream Port 1
Bus 3
Downstream Port 1
Root Port 2 Bus 2
Root Port 1
PCIe Dev 2
Bus 1
Switch
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Agenda
● Q35 chipset - Overview
● Q35 emulation
● Q35-only features
● Q35 limitations
● Q35 downstream
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Q35-only features
● PCIe “goodies”
– Extended configuration space (MMCFG)
– PCIe native hotplug
– Advanced Error Reporting (AER)
– Alternative Routing-ID Interpretation (ARI)
– Native Power Management
– Function Level Reset (FLR)
– Address Translation Services (ATS)
● AHCI storage controller
● vIOMMU emulation
● “Secure” Secure Boot
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Agenda
● Q35 chipset - Overview
● Q35 emulation
● Q35-only features
● Q35 limitations
● Q35 downstream
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Q35 limitations
● No support for legacy guests (Windows XP/2000).
● Questionable support for legacy QEMU devices.
● Limited IO space can affect the number of devices used by a single Q35 machine:
● Each device behind a separate PCI bridge.● Each bridge requires 4K IO range.● Several solutions available:
– Plug only PCIe devices into PCIe ports.– Use smaller/non-standard IO windows for bridges.– ...
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Agenda
● Q35 chipset - Overview
● Q35 emulation
● Q35-only features
● Q35 limitations
● Q35 use cases
![Page 17: Q35 - QEMU · 15 Q35 limitations No support for legacy guests (Windows XP/2000). Questionable support for legacy QEMU devices. Limited IO space can affect the number of devices used](https://reader035.vdocument.in/reader035/viewer/2022063001/5f12e547b1382150b801334e/html5/thumbnails/17.jpg)
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Q35 use cases
● Current use-cases:
– P2V (migrate physical machine to VM)
– Secure boot (+OVMF)
– vIOMMU (NFV)
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Thank you!