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| author | Igor Mammedov <imammedo@redhat.com> | 2021-01-21 11:15:04 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-02-08 14:43:54 +0100 |
| commit | 8db0b20415c129cf5e577a593a4a0372d90b7cc9 (patch) | |
| tree | 9efe01cbad73866594f7ac420926b1d5848e4482 /qemu-options.hx | |
| parent | 5ea9e9e239db83391a39c09f1de63c4099c20df5 (diff) | |
| download | focaccia-qemu-8db0b20415c129cf5e577a593a4a0372d90b7cc9.tar.gz focaccia-qemu-8db0b20415c129cf5e577a593a4a0372d90b7cc9.zip | |
machine: add missing doc for memory-backend option
Add documentation for '-machine memory-backend' CLI option and how to use it. And document that x-use-canonical-path-for-ramblock-id, is considered to be stable to make sure it won't go away by accident. x- was intended for unstable/iternal properties, and not supposed to be stable option. However it's too late to rename (drop x-) it as it would mean that users will have to mantain both x-use-canonical-path-for-ramblock-id (for QEMU 5.0-5.2) versions and prefix-less for later versions. Signed-off-by: Igor Mammedov <imammedo@redhat.com> Message-Id: <20210121161504.1007247-1-imammedo@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'qemu-options.hx')
| -rw-r--r-- | qemu-options.hx | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/qemu-options.hx b/qemu-options.hx index c09c4646e2..6c34c7050f 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -35,7 +35,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ " suppress-vmdesc=on|off disables self-describing migration (default=off)\n" " nvdimm=on|off controls NVDIMM support (default=off)\n" " memory-encryption=@var{} memory encryption object to use (default=none)\n" - " hmat=on|off controls ACPI HMAT support (default=off)\n", + " hmat=on|off controls ACPI HMAT support (default=off)\n" + " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n", QEMU_ARCH_ALL) SRST ``-machine [type=]name[,prop=value[,...]]`` @@ -96,6 +97,29 @@ SRST ``hmat=on|off`` Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support. The default is off. + + ``memory-backend='id'`` + An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options. + Allows to use a memory backend as main RAM. + + For example: + :: + -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on + -machine memory-backend=pc.ram + -m 512M + + Migration compatibility note: + a) as backend id one shall use value of 'default-ram-id', advertised by + machine type (available via ``query-machines`` QMP command), if migration + to/from old QEMU (<5.0) is expected. + b) for machine types 4.0 and older, user shall + use ``x-use-canonical-path-for-ramblock-id=off`` backend option + if migration to/from old QEMU (<5.0) is expected. + For example: + :: + -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off + -machine memory-backend=pc.ram + -m 512M ERST HXCOMM Deprecated by -machine |