Re: [PATCH] Deprecate pmem=on with non-DAX capable backend file
On Tue, Apr 27, 2021 at 04:48:48PM -0400, Eduardo Habkost wrote:
On Mon, Jan 11, 2021 at 03:33:32PM -0500, Igor Mammedov wrote:
> 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(a)redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd(a)redhat.com>
I'm queueing this for 6.1, after changing "since 6.0" to "since
6.1".
Sorry for letting it fall through the cracks.
This caused build failures[1] and I had to apply the following
fixup.
[1] https://gitlab.com/ehabkost/qemu/-/jobs/1216917482#L3444
Signed-off-by: Eduardo Habkost <ehabkost(a)redhat.com>
---
docs/system/deprecated.rst | 1 +
1 file changed, 1 insertion(+)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index cc8d810be1a..c55c4bceb00 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -257,6 +257,7 @@ is (a) not DAX capable or (b) not on a filesystem that support direct
mapping
of persistent memory, is not safe and may lead to data loss or corruption in case
of host crash.
Options are:
+
- modify VM configuration to set ``pmem=off`` to continue using fake NVDIMM
(without persistence guaranties) with backing file on non DAX storage
- move backing file to NVDIMM storage and keep ``pmem=on``
--
2.30.2
--
Eduardo