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- .. _Multi-process QEMU:
- Multi-process QEMU
- ==================
- This document describes how to configure and use multi-process qemu.
- For the design document refer to docs/devel/qemu-multiprocess.
- 1) Configuration
- ----------------
- multi-process is enabled by default for targets that enable KVM
- 2) Usage
- --------
- Multi-process QEMU requires an orchestrator to launch.
- Following is a description of command-line used to launch mpqemu.
- * Orchestrator:
- - The Orchestrator creates a unix socketpair
- - It launches the remote process and passes one of the
- sockets to it via command-line.
- - It then launches QEMU and specifies the other socket as an option
- to the Proxy device object
- * Remote Process:
- - QEMU can enter remote process mode by using the "remote" machine
- option.
- - The orchestrator creates a "remote-object" with details about
- the device and the file descriptor for the device
- - The remaining options are no different from how one launches QEMU with
- devices.
- - Example command-line for the remote process is as follows:
- /usr/bin/qemu-system-x86_64 \
- -machine x-remote \
- -device lsi53c895a,id=lsi0 \
- -drive id=drive_image2,file=/build/ol7-nvme-test-1.qcow2 \
- -device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0 \
- -object x-remote-object,id=robj1,devid=lsi0,fd=4,
- * QEMU:
- - Since parts of the RAM are shared between QEMU & remote process, a
- memory-backend-memfd is required to facilitate this, as follows:
- -object memory-backend-memfd,id=mem,size=2G
- - A "x-pci-proxy-dev" device is created for each of the PCI devices emulated
- in the remote process. A "socket" sub-option specifies the other end of
- unix channel created by orchestrator. The "id" sub-option must be specified
- and should be the same as the "id" specified for the remote PCI device
- - Example commandline for QEMU is as follows:
- -device x-pci-proxy-dev,id=lsi0,socket=3
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