1*639090d8SElena UfimtsevaMulti-process QEMU 2*639090d8SElena Ufimtseva================== 3*639090d8SElena Ufimtseva 4*639090d8SElena UfimtsevaThis document describes how to configure and use multi-process qemu. 5*639090d8SElena UfimtsevaFor the design document refer to docs/devel/qemu-multiprocess. 6*639090d8SElena Ufimtseva 7*639090d8SElena Ufimtseva1) Configuration 8*639090d8SElena Ufimtseva---------------- 9*639090d8SElena Ufimtseva 10*639090d8SElena Ufimtsevamulti-process is enabled by default for targets that enable KVM 11*639090d8SElena Ufimtseva 12*639090d8SElena Ufimtseva 13*639090d8SElena Ufimtseva2) Usage 14*639090d8SElena Ufimtseva-------- 15*639090d8SElena Ufimtseva 16*639090d8SElena UfimtsevaMulti-process QEMU requires an orchestrator to launch. 17*639090d8SElena Ufimtseva 18*639090d8SElena UfimtsevaFollowing is a description of command-line used to launch mpqemu. 19*639090d8SElena Ufimtseva 20*639090d8SElena Ufimtseva* Orchestrator: 21*639090d8SElena Ufimtseva 22*639090d8SElena Ufimtseva - The Orchestrator creates a unix socketpair 23*639090d8SElena Ufimtseva 24*639090d8SElena Ufimtseva - It launches the remote process and passes one of the 25*639090d8SElena Ufimtseva sockets to it via command-line. 26*639090d8SElena Ufimtseva 27*639090d8SElena Ufimtseva - It then launches QEMU and specifies the other socket as an option 28*639090d8SElena Ufimtseva to the Proxy device object 29*639090d8SElena Ufimtseva 30*639090d8SElena Ufimtseva* Remote Process: 31*639090d8SElena Ufimtseva 32*639090d8SElena Ufimtseva - QEMU can enter remote process mode by using the "remote" machine 33*639090d8SElena Ufimtseva option. 34*639090d8SElena Ufimtseva 35*639090d8SElena Ufimtseva - The orchestrator creates a "remote-object" with details about 36*639090d8SElena Ufimtseva the device and the file descriptor for the device 37*639090d8SElena Ufimtseva 38*639090d8SElena Ufimtseva - The remaining options are no different from how one launches QEMU with 39*639090d8SElena Ufimtseva devices. 40*639090d8SElena Ufimtseva 41*639090d8SElena Ufimtseva - Example command-line for the remote process is as follows: 42*639090d8SElena Ufimtseva 43*639090d8SElena Ufimtseva /usr/bin/qemu-system-x86_64 \ 44*639090d8SElena Ufimtseva -machine x-remote \ 45*639090d8SElena Ufimtseva -device lsi53c895a,id=lsi0 \ 46*639090d8SElena Ufimtseva -drive id=drive_image2,file=/build/ol7-nvme-test-1.qcow2 \ 47*639090d8SElena Ufimtseva -device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0 \ 48*639090d8SElena Ufimtseva -object x-remote-object,id=robj1,devid=lsi1,fd=4, 49*639090d8SElena Ufimtseva 50*639090d8SElena Ufimtseva* QEMU: 51*639090d8SElena Ufimtseva 52*639090d8SElena Ufimtseva - Since parts of the RAM are shared between QEMU & remote process, a 53*639090d8SElena Ufimtseva memory-backend-memfd is required to facilitate this, as follows: 54*639090d8SElena Ufimtseva 55*639090d8SElena Ufimtseva -object memory-backend-memfd,id=mem,size=2G 56*639090d8SElena Ufimtseva 57*639090d8SElena Ufimtseva - A "x-pci-proxy-dev" device is created for each of the PCI devices emulated 58*639090d8SElena Ufimtseva in the remote process. A "socket" sub-option specifies the other end of 59*639090d8SElena Ufimtseva unix channel created by orchestrator. The "id" sub-option must be specified 60*639090d8SElena Ufimtseva and should be the same as the "id" specified for the remote PCI device 61*639090d8SElena Ufimtseva 62*639090d8SElena Ufimtseva - Example commandline for QEMU is as follows: 63*639090d8SElena Ufimtseva 64*639090d8SElena Ufimtseva -device x-pci-proxy-dev,id=lsi0,socket=3 65