1.. _hostbridge_virt_hld:
2
3Host Bridge Emulation
4######################
5
6Overview
7********
8
9Host bridge emulation is based on PCI emulation; however, the host bridge
10emulation only sets the PCI configuration space. The Device Model (DM) sets the
11PCI configuration space for host bridge in the Service VM and then exposes it to
12the User VM to detect the PCI host bridge.
13
14PCI Host Bridge and Hierarchy
15*****************************
16
17For PCI host bridge emulation, the bus hierarchy is determined by ``acrn-dm``
18command line input. Using this command line, as an example::
19
20        acrn-dm -m $mem_size -s 0:0,hostbridge \
21        -s 5,virtio-console,@stdio:stdio_port \
22        -s 6,virtio-hyper_dmabuf \
23        -s 3,virtio-blk,/home/acrn/UserVM.img \
24        -s 4,virtio-net,tap=tap0,mac_seed=$mac_seed \
25        -s 7,virtio-rnd \
26        --ovmf /usr/share/acrn/bios/OVMF.fd \
27        $logger_setting \
28        $vm_name
29
30the bus hierarchy would be:
31
32.. code-block:: console
33
34   # lspci
35   00:00.0 Host bridge: Network Appliance Corporation Device 1275
36   00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
37   00:03.0 SCSI storage controller: Red Hat, Inc. Virtio block device
38   00:05.0 Serial controller: Red Hat, Inc. Virtio console
39   00:06.0 RAM memory: Intel Corporation Device 8606
40   00:08.0 Network and computing encryption device: Red Hat, Inc. Virtio RNG
41   00:09.0 Ethernet controller: Red Hat, Inc. Virtio network device
42