From: Elena Ufimtseva <elena.ufimts...@oracle.com> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com> Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com> Signed-off-by: John G Johnson <john.g.john...@oracle.com> --- Changes in v3: - since the changes were made to use existing device/drive options, the document was modified to reflect this. --- docs/qemu-multiprocess.txt | 86 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 docs/qemu-multiprocess.txt
diff --git a/docs/qemu-multiprocess.txt b/docs/qemu-multiprocess.txt new file mode 100644 index 0000000..c29f4df --- /dev/null +++ b/docs/qemu-multiprocess.txt @@ -0,0 +1,86 @@ +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 +-------- + +To start qemu with devices intended to run in a separate emulation +process without libvirtd support, the following should be used on QEMU +command line. As of now, we only support the emulation of lsi53c895a +in a separate process + +* 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 + +* The devices to be emulated in the separate process are defined as + before with addition of "rid" suboption that serves as a remote group + identificator. + + -device <device options>,rid="remote process id" + + For exmaple, for non multi-process qemu: + -device lsi53c895a,id=scsi0 device + -device scsi-hd,drive=drive0,bus=scsi0.0,scsi-id=0 + -drive id=drive0,file=data-disk.img + + and for multi-process qemu and no libvirt + support (i.e. QEMU forks child processes): + -device lsi53c895a,id=scsi0,rid=0 + -device scsi-hd,drive=drive0,bus=scsi0.0,scsi-id=0,rid="0" + +* The command-line options for the remote process is added to the "command" + suboption of the newly added "-remote" option. + + -remote [socket],rid=,command="..." + + The drives to be emulated by the remote process are specified as part of + this command sub-option. The device to be used to connect to the monitor + is also specified as part of this suboption. + + For example, the following option adds a drive and monitor to the remote + process: + -remote rid=0,command="-drive id=drive0,,file=data-disk.img -monitor unix:/home/qmp-sock,,server,,nowait" + + Note: There's an issue with this "command" subtion which we are in the + process of fixing. To work around this issue, it requires additional + "comma" characters as illustrated above, and in the example below. + +* Example QEMU command-line to launch lsi53c895a in a remote process + + #/bin/sh + qemu-system-x86_64 \ + -name "OL7.4" \ + -machine q35,accel=kvm \ + -smp sockets=1,cores=1,threads=1 \ + -cpu host \ + -m 2048 \ + -object memory-backend-file,id=mem,mem-path=/dev/shm/,size=2G,share=on \ + -numa node,memdev=mem \ + -device virtio-scsi-pci,id=virtio_scsi_pci0 \ + -drive id=drive_image1,if=none,format=raw,file=/root/ol7.qcow2 \ + -device scsi-hd,id=image1,drive=drive_image1,bus=virtio_scsi_pci0.0 \ + -boot d \ + -monitor stdio \ + -vnc :0 \ + -device lsi53c895a,id=lsi0,remote,rid=8,command="qemu-scsi-dev" \ + -device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0,remote,rid=8,command="qemu-scsi-dev"\ + -remote rid=8,command="-drive id=drive_image2,,file=/root/remote-process-disk.img -monitor unix:/home/qmp-sock,,server,,nowait" + + We could connect to the monitor using the following command: + socat /home/qmp-sock stdio + + After hotplugging disks to the remote process, please execute the + following command in the guest to refresh the list of storage devices: + rescan_scsi_bus.sh -a -- 1.8.3.1
