David Hildenbrand <da...@redhat.com> writes: > On 23.04.21 13:21, Markus Armbruster wrote: >> David Hildenbrand <da...@redhat.com> writes: >> >>> On 23.04.21 13:00, Markus Armbruster wrote: >>>> David Hildenbrand <da...@redhat.com> writes: >>>> >>>>> Let's include the new property. >>>>> >>>>> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> >>>>> Cc: Eric Blake <ebl...@redhat.com> >>>>> Cc: Markus Armbruster <arm...@redhat.com> >>>>> Cc: Igor Mammedov <imamm...@redhat.com> >>>>> Signed-off-by: David Hildenbrand <da...@redhat.com> >>>>> --- >>>>> hw/core/machine-qmp-cmds.c | 1 + >>>>> qapi/machine.json | 4 ++++ >>>>> 2 files changed, 5 insertions(+) >>>>> >>>>> diff --git a/hw/core/machine-qmp-cmds.c b/hw/core/machine-qmp-cmds.c >>>>> index d41db5b93b..2d135ecdd0 100644 >>>>> --- a/hw/core/machine-qmp-cmds.c >>>>> +++ b/hw/core/machine-qmp-cmds.c >>>>> @@ -175,6 +175,7 @@ static int query_memdev(Object *obj, void *opaque) >>>>> m->dump = object_property_get_bool(obj, "dump", &error_abort); >>>>> m->prealloc = object_property_get_bool(obj, "prealloc", >>>>> &error_abort); >>>>> m->share = object_property_get_bool(obj, "share", >>>>> &error_abort); >>>>> + m->reserve = object_property_get_bool(obj, "reserve", >>>>> &error_abort); >>>>> m->policy = object_property_get_enum(obj, "policy", >>>>> "HostMemPolicy", >>>>> &error_abort); >>>>> host_nodes = object_property_get_qobject(obj, >>>>> diff --git a/qapi/machine.json b/qapi/machine.json >>>>> index 32650bfe9e..5932139d20 100644 >>>>> --- a/qapi/machine.json >>>>> +++ b/qapi/machine.json >>>>> @@ -798,6 +798,9 @@ >>>>> # >>>>> # @share: whether memory is private to QEMU or shared (since 6.1) >>>>> # >>>>> +# @reserve: whether swap space (or huge pages) was reserved if applicable >>>>> +# (since 6.1) >>>>> +# >>>>> # @host-nodes: host nodes for its memory policy >>>>> # >>>>> # @policy: memory policy of memory backend >>>>> @@ -812,6 +815,7 @@ >>>>> 'dump': 'bool', >>>>> 'prealloc': 'bool', >>>>> 'share': 'bool', >>>>> + 'reserve': 'bool', >>>>> 'host-nodes': ['uint16'], >>>>> 'policy': 'HostMemPolicy' }} >>>> >>>> Double-checking: true means definitely reserved, and false means >>>> definitely not reserved. Correct? >>> >>> True means "reserved if applicable" which means "not reserved if not >>> applicable". False means "definitely not reserved". >>> >>> (any recommendation how to rephrase are appreciated; I tried my best -- >>> this interface here makes it especially hard -- it's easier for the >>> property itself) >> >> When is it "applicable"? > > When the OS supports it for the memory type and it hasn't been disabled. > > Linux handling as described in > [PATCH v6 09/15] util/mmap-alloc: Support RAM_NORESERVE via > MAP_NORESERVE under Linux > and > > https://www.kernel.org/doc/Documentation/vm/overcommit-accounting > > Summary *without* MAP_NORESERVE: > > a) !Hugetlbfs with Memory overcommit disabled via > ("/proc/sys/vm/overcommit_memory == 2"): never > > b) !Hugetlbfs with Memory overcommit enabled > 1) Shared mappings on files: never > > 2) Private mappings on files: only when writable (for us always) > > 3) Shared anonymous memory: always > > 4) Private anonymous memory: only when writable (for us always) > > c) Hugetlbfs: Always > > > Under Windows: always. On other POSIX besides Linux -- don't know.
Would working some of this into the doc comment help users of the interface? Up to you.
