Host Bridge Emulation


Host bridge emulation is based on PCI emulation; however, the host bridge emulation only sets the PCI configuration space. The Device Model (DM) sets the PCI configuration space for host bridge in the Service VM and then exposes it to the User VM to detect the PCI host bridge.

PCI Host Bridge and Hierarchy

For PCI host bridge emulation, the bus hierarchy is determined by acrn-dm command line input. Using this command line, as an example:

acrn-dm -m $mem_size -s 0:0,hostbridge \
-s 5,virtio-console,@stdio:stdio_port \
-s 6,virtio-hyper_dmabuf \
-s 3,virtio-blk,/home/acrn/UserVM.img \
-s 4,virtio-net,tap=tap0,mac_seed=$mac_seed \
-s 7,virtio-rnd \
--ovmf /usr/share/acrn/bios/OVMF.fd \
$logger_setting \

the bus hierarchy would be:

# lspci
00:00.0 Host bridge: Network Appliance Corporation Device 1275
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:03.0 SCSI storage controller: Red Hat, Inc. Virtio block device
00:05.0 Serial controller: Red Hat, Inc. Virtio console
00:06.0 RAM memory: Intel Corporation Device 8606
00:08.0 Network and computing encryption device: Red Hat, Inc. Virtio RNG
00:09.0 Ethernet controller: Red Hat, Inc. Virtio network device