commit cdcf766d0b0364165ba9e5ceacfdf37c8b1fe4ae
author Igor Mammedov <imammedo@redhat.com> Mon Jan 11 15:33:32 2021 -0500
committer Eduardo Habkost <ehabkost@redhat.com> Tue Jul 06 18:05:16 2021 -0400
tree 27dae453b720de1bc58c6eb425f9efbf996f9b3e
parent 80cc1a0dd19cc414ddaa3f1b9b6ef91e3ebc12b2

Deprecate pmem=on with non-DAX capable backend file

It is not safe to pretend that emulated NVDIMM supports
persistence while backend actually failed to enable it
and used non-persistent mapping as fall back.
Instead of falling-back, QEMU should be more strict and
error out with clear message that it's not supported.
So if user asks for persistence (pmem=on), they should
store backing file on NVDIMM.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210111203332.740815-1-imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

util/mmap-alloc.c

diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 838e286..893d864 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -225,6 +225,8 @@
                     "crash.\n", file_name);
             g_free(proc_link);
             g_free(file_name);
+            warn_report("Using non DAX backing file with 'pmem=on' option"
+                        " is deprecated");
         }
         /*
          * If mmap failed with MAP_SHARED_VALIDATE | MAP_SYNC, we will try