Re: [PATCH REBASE 7/7] qemu: Use memory-backend-* for regular guest memory

On Tue, 15 Sep 2020 10:54:46 +0200 Michal Privoznik <mprivozn(a)redhat.com&gt; wrote: > On 9/8/20 3:55 PM, Ján Tomko wrote: > > On a Tuesday in 2020, Michal Privoznik wrote: > > >> diff --git > >> a/tests/qemuxml2argvdata/memfd-memory-default-hugepage.x86_64-latest.args > >> b/tests/qemuxml2argvdata/memfd-memory-default-hugepage.x86_64-latest.args > >> index 5d256c42bc..b43e7d9c3c 100644 > >> --- > >> a/tests/qemuxml2argvdata/memfd-memory-default-hugepage.x86_64-latest.args > >> +++ > >> b/tests/qemuxml2argvdata/memfd-memory-default-hugepage.x86_64-latest.args > >> @@ -12,14 +12,16 @@ QEMU_AUDIO_DRV=none \ > >> -S \ > >> -object secret,id=masterKey0,format=raw,\ > >> file=/tmp/lib/domain--1-instance-00000092/master-key.aes \ > >> --machine pc-i440fx-2.3,accel=kvm,usb=off,dump-guest-core=off \ > >> +-machine pc-i440fx-2.3,accel=kvm,usb=off,dump-guest-core=off,\ > >> +memory-backend=pc.ram \ > >> -cpu qemu64 \ > >> -m 14336 \ > >> --mem-prealloc \ > >> +-object memory-backend-memfd,id=pc.ram,hugetlb=yes,hugetlbsize=2097152,\ > >> +share=yes,prealloc=yes,size=15032385536 \ > >> -overcommit mem-lock=off \ > >> -smp 8,sockets=1,dies=1,cores=8,threads=1 \ > >> -object > >> memory-backend-memfd,id=ram-node0,hugetlb=yes,hugetlbsize=2097152,\ > >> -share=yes,size=15032385536,host-nodes=3,policy=preferred \ > >> +share=yes,prealloc=yes,size=15032385536,host-nodes=3,policy=preferred \ > >> -numa node,nodeid=0,cpus=0-7,memdev=ram-node0 \ > >> -uuid 126f2720-6f8e-45ab-a886-ec9277079a67 \ > >> -display none \ > > > > Should we format all the fields twice in these cases? > > Ah, good question. Honestly, I don't remember, it was slightly longer > ago that I've written these patches. Igor, do you perhaps remember > whether libvirt needs to specify both: -machine memory-backend=$id and > -object memory-backend-*,id=$id? the later defines backend and the former uses it, short answer is yes. you do not need --mem-prealloc if you explicitly set "prealloc=yes" on backend. I'd prefer if libvirt stopped using old -mem-prealloc and -mem-path in favor of explicit properties on backend, so QEMU could deprecate it and drop aliasing code which uses global properties hack.