[Qemu-devel] [PATCH v4 3/3] numa: deprecate implict memory distribution between nodes

[Igor Mammedov <imammedo@redhat.com>]

Implicit RAM distribution between nodes has exactly the same issues as:
  "numa: deprecate 'mem' parameter of '-numa node' option"
only with QEMU being the user that's 'adding' 'mem' parameter.

Deprecate it, to get it out of the way so that we could consolidate
guest RAM allocation using memory backends making it consistent and
possibly later on transition to using memory devices instead of
adhoc memory mapping for the initial RAM.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 numa.c               | 3 +++
 qemu-deprecated.texi | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/numa.c b/numa.c
index 2205773..6d45a1f 100644
--- a/numa.c
+++ b/numa.c
@@ -409,6 +409,9 @@ void numa_complete_configuration(MachineState *ms)
         if (i == nb_numa_nodes) {
             assert(mc->numa_auto_assign_ram);
             mc->numa_auto_assign_ram(mc, numa_info, nb_numa_nodes, ram_size);
+            warn_report("Default splitting of RAM between nodes is deprecated,"
+                        " Use '-numa node,memdev' to explictly define RAM"
+                        " allocation per node");
         }
 
         numa_total = 0;
diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
index eb347f5..c744ba9 100644
--- a/qemu-deprecated.texi
+++ b/qemu-deprecated.texi
@@ -98,6 +98,14 @@ In future new machine versions will not accept the option but it will still
 work with old machine types. User can check QAPI schema to see if the legacy
 option is supported by looking at MachineInfo::numa-mem-supported property.
 
+@subsection -numa node (without memory specified) (since 4.1)
+
+Splitting RAM by default between NUMA nodes has the same issues as @option{mem}
+parameter described above with the difference that the role of the user plays
+QEMU using implicit generic or board specific splitting rule.
+Use @option{memdev} with @var{memory-backend-ram} backend or @option{mem} (if
+it's supported by used machine type) to define mapping explictly instead.
+
 @section QEMU Machine Protocol (QMP) commands
 
 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
-- 
2.7.4