2021-01-29 19:46:03 +03:00
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Multi-process QEMU
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==================
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This document describes how to configure and use multi-process qemu.
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For the design document refer to docs/devel/qemu-multiprocess.
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1) Configuration
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----------------
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multi-process is enabled by default for targets that enable KVM
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2) Usage
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--------
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Multi-process QEMU requires an orchestrator to launch.
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Following is a description of command-line used to launch mpqemu.
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* Orchestrator:
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- The Orchestrator creates a unix socketpair
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- It launches the remote process and passes one of the
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sockets to it via command-line.
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- It then launches QEMU and specifies the other socket as an option
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to the Proxy device object
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* Remote Process:
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- QEMU can enter remote process mode by using the "remote" machine
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option.
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- The orchestrator creates a "remote-object" with details about
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the device and the file descriptor for the device
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- The remaining options are no different from how one launches QEMU with
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devices.
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- Example command-line for the remote process is as follows:
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/usr/bin/qemu-system-x86_64 \
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-machine x-remote \
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-device lsi53c895a,id=lsi0 \
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-drive id=drive_image2,file=/build/ol7-nvme-test-1.qcow2 \
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-device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0 \
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2021-07-13 03:47:18 +03:00
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-object x-remote-object,id=robj1,devid=lsi0,fd=4,
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2021-01-29 19:46:03 +03:00
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* QEMU:
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- Since parts of the RAM are shared between QEMU & remote process, a
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memory-backend-memfd is required to facilitate this, as follows:
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-object memory-backend-memfd,id=mem,size=2G
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- A "x-pci-proxy-dev" device is created for each of the PCI devices emulated
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in the remote process. A "socket" sub-option specifies the other end of
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unix channel created by orchestrator. The "id" sub-option must be specified
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and should be the same as the "id" specified for the remote PCI device
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- Example commandline for QEMU is as follows:
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-device x-pci-proxy-dev,id=lsi0,socket=3
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