12c46bc24SAlex Bennée.. _Multi-process QEMU: 22c46bc24SAlex Bennée 3639090d8SElena UfimtsevaMulti-process QEMU 4639090d8SElena Ufimtseva================== 5639090d8SElena Ufimtseva 6639090d8SElena UfimtsevaThis document describes how to configure and use multi-process qemu. 77771e8b8SJagannathan RamanFor the design document refer to docs/devel/multi-process.rst. 8639090d8SElena Ufimtseva 9639090d8SElena Ufimtseva1) Configuration 10639090d8SElena Ufimtseva---------------- 11639090d8SElena Ufimtseva 12639090d8SElena Ufimtsevamulti-process is enabled by default for targets that enable KVM 13639090d8SElena Ufimtseva 14639090d8SElena Ufimtseva 15639090d8SElena Ufimtseva2) Usage 16639090d8SElena Ufimtseva-------- 17639090d8SElena Ufimtseva 18639090d8SElena UfimtsevaMulti-process QEMU requires an orchestrator to launch. 19639090d8SElena Ufimtseva 20639090d8SElena UfimtsevaFollowing is a description of command-line used to launch mpqemu. 21639090d8SElena Ufimtseva 22639090d8SElena Ufimtseva* Orchestrator: 23639090d8SElena Ufimtseva 24639090d8SElena Ufimtseva - The Orchestrator creates a unix socketpair 25639090d8SElena Ufimtseva 26639090d8SElena Ufimtseva - It launches the remote process and passes one of the 27639090d8SElena Ufimtseva sockets to it via command-line. 28639090d8SElena Ufimtseva 29639090d8SElena Ufimtseva - It then launches QEMU and specifies the other socket as an option 30639090d8SElena Ufimtseva to the Proxy device object 31639090d8SElena Ufimtseva 32639090d8SElena Ufimtseva* Remote Process: 33639090d8SElena Ufimtseva 34639090d8SElena Ufimtseva - QEMU can enter remote process mode by using the "remote" machine 35639090d8SElena Ufimtseva option. 36639090d8SElena Ufimtseva 37639090d8SElena Ufimtseva - The orchestrator creates a "remote-object" with details about 38639090d8SElena Ufimtseva the device and the file descriptor for the device 39639090d8SElena Ufimtseva 40639090d8SElena Ufimtseva - The remaining options are no different from how one launches QEMU with 41639090d8SElena Ufimtseva devices. 42639090d8SElena Ufimtseva 43639090d8SElena Ufimtseva - Example command-line for the remote process is as follows: 44639090d8SElena Ufimtseva 45639090d8SElena Ufimtseva /usr/bin/qemu-system-x86_64 \ 46639090d8SElena Ufimtseva -machine x-remote \ 47639090d8SElena Ufimtseva -device lsi53c895a,id=lsi0 \ 48639090d8SElena Ufimtseva -drive id=drive_image2,file=/build/ol7-nvme-test-1.qcow2 \ 49639090d8SElena Ufimtseva -device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0 \ 5045b09cb1SDongli Zhang -object x-remote-object,id=robj1,devid=lsi0,fd=4, 51639090d8SElena Ufimtseva 52639090d8SElena Ufimtseva* QEMU: 53639090d8SElena Ufimtseva 54639090d8SElena Ufimtseva - Since parts of the RAM are shared between QEMU & remote process, a 55639090d8SElena Ufimtseva memory-backend-memfd is required to facilitate this, as follows: 56639090d8SElena Ufimtseva 57639090d8SElena Ufimtseva -object memory-backend-memfd,id=mem,size=2G 58639090d8SElena Ufimtseva 59639090d8SElena Ufimtseva - A "x-pci-proxy-dev" device is created for each of the PCI devices emulated 60639090d8SElena Ufimtseva in the remote process. A "socket" sub-option specifies the other end of 61639090d8SElena Ufimtseva unix channel created by orchestrator. The "id" sub-option must be specified 62639090d8SElena Ufimtseva and should be the same as the "id" specified for the remote PCI device 63639090d8SElena Ufimtseva 64639090d8SElena Ufimtseva - Example commandline for QEMU is as follows: 65639090d8SElena Ufimtseva 66639090d8SElena Ufimtseva -device x-pci-proxy-dev,id=lsi0,socket=3 67