Re: [libvirt] [Qemu-devel] [PATCH v4 0/3] numa: deprecate '-numa node, mem' and default memory distribution

Changes since v3: - simplify series by dropping idea of showing property values in "qom-list-properties" and use MachineInfo in QAPI schema instead Changes since v2: - taking in account previous review, implement a way for mgmt to intospect if '-numa node,mem' is supported by machine type as suggested by Daniel at https://www.mail-archive.com/qemu-devel@nongnu.org/msg601220.html * ammend "qom-list-properties" to show property values * add "numa-mem-supported" machine property to reflect if '-numa node,mem=SZ' is supported. It culd be used with '-machine none' or at runtime with --preconfig before numa memory mapping are configured * minor fixes to deprecation documentation mentioning "numa-mem-supported" property 1) "I'm considering to deprecating -mem-path/prealloc CLI options and replacing them with a single memdev Machine property to allow interested users to pick used backend for initial RAM (fixes mixed -mem-path+hostmem backends issues) and as a transition step to modeling initial RAM as a Device instead of (ab)using MemoryRegion APIs." (for more details see: https://www.mail-archive.com/qemu-devel@nongnu.org/msg596314.html) However there is a couple of roadblocks on the way (s390x and numa memory handling). I think I finally thought out a way to hack s390x in migration compatible manner, but I don't see any way to do it for -numa node,mem and default RAM assignement to nodes. Considering both numa usecases aren't meaningfully using NUMA (aside guest side testing) and could be replaced with explicitly used memdev parameter, I'd like to propose removing these fake NUMA friends on new machine types, hence this deprecation. And once the last machie type that supported the option is removed we would be able to remove option altogether. As result of removing deprecated options and replacing initial RAM allocation with 'memdev's (1), QEMU will allocate guest RAM in consistent way, fixing mixed use-case and allowing boards to move towards modelling initial RAM as Device(s). Which in its own turn should allow to cleanup NUMA/HMP/memory accounting code more by dropping ad-hoc node_mem tracking and reusing memory device enumeration instead.

Reference to previous versions: * https://www.mail-archive.com/qemu-devel@nongnu.org/msg617694.html CC: libvir-list(a)redhat.com CC: ehabkost(a)redhat.com CC: pbonzini(a)redhat.com CC: berrange(a)redhat.com CC: armbru(a)redhat.com Igor Mammedov (3): machine: show if CLI option '-numa node,mem' is supported in QAPI schema numa: deprecate 'mem' parameter of '-numa node' option numa: deprecate implict memory distribution between nodes include/hw/boards.h | 3 +++ hw/arm/virt.c | 1 + hw/i386/pc.c | 1 + hw/ppc/spapr.c | 1 + numa.c | 5 +++++ qapi/misc.json | 5 ++++- qemu-deprecated.texi | 24 ++++++++++++++++++++++++ vl.c | 1 + 8 files changed, 40 insertions(+), 1 deletion(-)