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+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.
+
+scripts/mpqemu-launcher-perf-mode.py launches in "perf" mode. In this mode,
+the same QEMU process connects to multiple remote devices, each emulated in
+a separate process.
+
+As of now, we only support the emulation of lsi53c895a in a separate process.
+
+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:
+
+ - The first command-line option in the remote process is one of the
+ sockets created by the Orchestrator
+
+ - The remaining options are no different from how one launches QEMU with
+ devices. The only other requirement is each PCI device must have a
+ unique ID specified to it. This is needed to pair remote device with the
+ Proxy object.
+
+ - Example command-line for the remote process is as follows:
+
+ /usr/bin/qemu-scsu-dev 4 \
+ -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
+
+* QEMU:
+
+ - Since parts of the RAM are shared between QEMU & remote process, a
+ memory-backend-file is required to facilitate this, as follows:
+
+ -object memory-backend-file,id=mem,mem-path=/dev/shm/,size=4096M,share=on
+
+ - 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
+
+* Monitor / QMP:
+
+ - The remote process supports QEMU monitor. It could be specified using the
+ "-monitor" or "-qmp" command-line options
+
+ - As an example, one could connect to the monitor by adding the following
+ to the command-line of the remote process
+
+ -monitor unix:/home/qmp-sock,server,nowait
+
+ - The user could connect to the monitor using the qmp script or using
+ "socat" as outlined below:
+
+ socat /home/qmp-sock stdio
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+#!/usr/bin/env python3
+
+import socket
+import os
+import subprocess
+import time
+
+PROC_QEMU='/usr/bin/qemu-system-x86_64'
+
+PROC_REMOTE='/usr/bin/qemu-scsi-dev'
+
+proxy_1, remote_1 = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+proxy_2, remote_2 = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+proxy_3, remote_3 = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+
+remote_cmd_1 = [ PROC_REMOTE, \
+ str(remote_1.fileno()), \
+ '-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', \
+ ]
+
+remote_cmd_2 = [ PROC_REMOTE, \
+ str(remote_2.fileno()), \
+ '-device', 'lsi53c895a,id=lsi2', \
+ '-drive', 'id=drive_image2,' \
+ 'file=/build/ol7-nvme-test-2.qcow2', \
+ '-device', 'scsi-hd,id=drive2,drive=drive_image2,' \
+ 'bus=lsi2.0,scsi-id=0' \
+ ]
+
+remote_cmd_3 = [ PROC_REMOTE, \
+ str(remote_3.fileno()), \
+ '-device', 'lsi53c895a,id=lsi3', \
+ '-drive', 'id=drive_image3,' \
+ 'file=/build/ol7-nvme-test-3.qcow2', \
+ '-device', 'scsi-hd,id=drive3,drive=drive_image3,' \
+ 'bus=lsi3.0,scsi-id=0' \
+ ]
+
+proxy_cmd = [ PROC_QEMU, \
+ '-name', 'OL7.4', \
+ '-machine', 'q35,accel=kvm', \
+ '-smp', 'sockets=1,cores=1,threads=1', \
+ '-m', '2048', \
+ '-object', 'memory-backend-file,id=sysmem-file,' \
+ 'mem-path=/dev/shm/test-mem,size=2G,share=on', \
+ '-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,' \
+ 'socket='+str(proxy_1.fileno()), \
+ '-device', 'pci-proxy-dev,id=lsi2,' \
+ 'socket='+str(proxy_2.fileno()), \
+ '-device', 'pci-proxy-dev,id=lsi3,' \
+ 'socket='+str(proxy_3.fileno()) \
+ ]
+
+
+pid = os.fork();
+if pid == 0:
+ # In remote_1
+ print('Launching Remote process 1');
+ process = subprocess.Popen(remote_cmd_1, pass_fds=[remote_1.fileno()])
+ os._exit(0)
+
+
+pid = os.fork();
+if pid == 0:
+ # In remote_2
+ print('Launching Remote process 2');
+ process = subprocess.Popen(remote_cmd_2, pass_fds=[remote_2.fileno()])
+ os._exit(0)
+
+
+pid = os.fork();
+if pid == 0:
+ # In remote_3
+ print('Launching Remote process 3');
+ process = subprocess.Popen(remote_cmd_3, pass_fds=[remote_3.fileno()])
+ os._exit(0)
+
+
+print('Launching Proxy process');
+process = subprocess.Popen(proxy_cmd, pass_fds=[proxy_1.fileno(), \
+ proxy_2.fileno(), proxy_3.fileno()])
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+#!/usr/bin/env python3
+import socket
+import os
+import subprocess
+import time
+
+PROC_QEMU='/usr/bin/qemu-system-x86_64'
+
+PROC_REMOTE='/usr/bin/qemu-scsi-dev'
+
+proxy, remote = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+
+remote_cmd = [ PROC_REMOTE, \
+ str(remote.fileno()), \
+ '-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', \
+ '-device', 'lsi53c895a,id=lsi2', \
+ '-drive', 'id=drive_image2,file=/build/ol7-nvme-test-2.qcow2', \
+ '-device', 'scsi-hd,id=drive2,drive=drive_image2,bus=lsi2.0,' \
+ 'scsi-id=0' \
+ ]
+
+proxy_cmd = [ PROC_QEMU, \
+ '-name', 'OL7.4', \
+ '-machine', 'q35,accel=kvm', \
+ '-smp', 'sockets=1,cores=1,threads=1', \
+ '-m', '2048', \
+ '-object', 'memory-backend-file,id=sysmem-file,' \
+ 'mem-path=/dev/shm/test-mem,size=2G,share=on', \
+ '-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,socket='+str(proxy.fileno()), \
+ '-device', 'pci-proxy-dev,id=lsi2,socket='+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()])