@@ -3058,6 +3058,8 @@ F: include/hw/pci/memory-sync.h
F: hw/remote/iohub.c
F: include/hw/remote/iohub.h
F: docs/devel/multi-process.rst
+F: scripts/mpqemu-launcher.py
+F: scripts/mpqemu-launcher-perf-mode.py
Build and test automation
-------------------------
new file mode 100644
@@ -0,0 +1,67 @@
+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
+----------------
+
+To enable support for multi-process add --enable-mpqemu
+to the list of options for the "configure" script.
+
+
+2) Usage
+--------
+
+Multi-process QEMU requires an orchestrator to launch. Please refer to a
+light-weight python based orchestrator for mpqemu in
+scripts/mpqemu-launcher.py to lauch QEMU in multi-process mode.
+
+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 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 remote-object,id=robj1,devid=lsi1,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 "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 pci-proxy-dev,id=lsi0,socket=3
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+#!/usr/bin/env python3
+import socket
+import os
+import subprocess
+import time
+
+PROC_QEMU='/usr/bin/qemu-system-x86_64'
+
+proxy, remote = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+
+remote_cmd = [ PROC_QEMU, \
+ '-machine', 'remote', \
+ '-device', 'lsi53c895a,id=lsi1', \
+ '-drive', 'id=drive_image1,file=/build/ol7-nvme-test-1.qcow2', \
+ '-device', 'scsi-hd,id=drive1,drive=drive_image1,bus=lsi1.0,' \
+ 'scsi-id=0', \
+ '-object', \
+ 'remote-object,id=robj1,devid=lsi1,fd='+str(remote.fileno()), \
+ '-nographic', \
+ ]
+
+proxy_cmd = [ PROC_QEMU, \
+ '-name', 'OL7.4', \
+ '-machine', 'q35,accel=kvm', \
+ '-smp', 'sockets=1,cores=1,threads=1', \
+ '-m', '2048', \
+ '-object', 'memory-backend-memfd,id=sysmem-file,size=2G', \
+ '-numa', 'node,memdev=sysmem-file', \
+ '-device', 'virtio-scsi-pci,id=virtio_scsi_pci0', \
+ '-drive', 'id=drive_image1,if=none,format=qcow2,' \
+ 'file=/home/ol7-hdd-1.qcow2', \
+ '-device', 'scsi-hd,id=image1,drive=drive_image1,' \
+ 'bus=virtio_scsi_pci0.0', \
+ '-boot', 'd', \
+ '-vnc', ':0', \
+ '-device', 'pci-proxy-dev,id=lsi1,fd='+str(proxy.fileno()), \
+ ]
+
+
+pid = os.fork();
+
+if pid:
+ # In Proxy
+ print('Launching QEMU with Proxy object');
+ process = subprocess.Popen(proxy_cmd, pass_fds=[proxy.fileno()])
+else:
+ # In remote
+ print('Launching Remote process');
+ process = subprocess.Popen(remote_cmd, pass_fds=[remote.fileno()])