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There are a some scenarios in which we want to prealloc guest memory (e.g. when requested in domain XML, when using hugepages, etc.). With 'regular' <memory/> models (like 'dimm', 'nvdimm' or 'virtio-pmem') or regular guest memory it is corresponding memory-backend-* object that ends up with .prealloc attribute set. And that's desired because neither of those devices can change its size on the fly. However, with virtio-mem model things are a bit different. While one can set .prealloc attribute on corresponding memory-backend-* object it doesn't make much sense, because virtio-mem can inflate/deflate on the fly, i.e. change how big of a portion of the memory-backend-* object is exposed to the guest. For instance, from a say 4GiB module only a half can be exposed to the guest. Therefore, it doesn't make much sense to preallocate whole 4GiB and keep them allocated. But we still want the part exposed to the guest preallocated (when conditions described at the beginning are met). Having said that, with new enough QEMU the virtio-mem-pci device gained new attribute ".prealloc" which instructs the device to talk to the memory backend object and allocate only the requested portion of memory. Now, that our algorithm for setting .prealloc was isolated in a single function, the function can be called when constructing cmd line for virtio-mem-pci device. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
43 lines
2.3 KiB
Plaintext
43 lines
2.3 KiB
Plaintext
LC_ALL=C \
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PATH=/bin \
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HOME=/tmp/lib/domain--1-QEMUGuest1 \
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USER=test \
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LOGNAME=test \
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XDG_DATA_HOME=/tmp/lib/domain--1-QEMUGuest1/.local/share \
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XDG_CACHE_HOME=/tmp/lib/domain--1-QEMUGuest1/.cache \
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XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \
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/usr/bin/qemu-system-x86_64 \
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-name guest=QEMUGuest1,debug-threads=on \
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-S \
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-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/tmp/lib/domain--1-QEMUGuest1/master-key.aes"}' \
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-machine pc,usb=off,dump-guest-core=off \
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-accel kvm \
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-cpu qemu64 \
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-m size=2095104k,slots=16,maxmem=1099511627776k \
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-overcommit mem-lock=off \
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-smp 2,sockets=2,dies=1,cores=1,threads=1 \
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-object '{"qom-type":"memory-backend-ram","id":"ram-node0","size":2145386496}' \
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-numa node,nodeid=0,cpus=0-1,memdev=ram-node0 \
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-object '{"qom-type":"memory-backend-ram","id":"memvirtiomem0","reserve":false,"size":1073741824}' \
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-device '{"driver":"virtio-mem-pci","node":0,"block-size":2097152,"requested-size":536870912,"memdev":"memvirtiomem0","id":"virtiomem0","bus":"pci.0","addr":"0x2"}' \
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-object '{"qom-type":"memory-backend-file","id":"memvirtiomem1","mem-path":"/dev/hugepages2M/libvirt/qemu/-1-QEMUGuest1","reserve":false,"size":2147483648,"host-nodes":[1,2,3],"policy":"bind"}' \
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-device '{"driver":"virtio-mem-pci","node":0,"block-size":2097152,"requested-size":1073741824,"memdev":"memvirtiomem1","prealloc":true,"id":"virtiomem1","bus":"pci.0","addr":"0x3"}' \
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-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
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-display none \
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-no-user-config \
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-nodefaults \
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-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \
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-mon chardev=charmonitor,id=monitor,mode=control \
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-rtc base=utc \
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-no-shutdown \
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-no-acpi \
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-boot strict=on \
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-device '{"driver":"piix3-usb-uhci","id":"usb","bus":"pci.0","addr":"0x1.0x2"}' \
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-blockdev '{"driver":"host_device","filename":"/dev/HostVG/QEMUGuest1","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
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-blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"raw","file":"libvirt-1-storage"}' \
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-device '{"driver":"ide-hd","bus":"ide.0","unit":0,"drive":"libvirt-1-format","id":"ide0-0-0","bootindex":1}' \
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-audiodev '{"id":"audio1","driver":"none"}' \
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-device '{"driver":"virtio-balloon-pci","id":"balloon0","bus":"pci.0","addr":"0x4"}' \
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-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
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-msg timestamp=on
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