Re: [PATCH] docs/nvdimm: add 'pmem=on' for the device dax backend file

[Stefan Hajnoczi]

On Wed, Jul 15, 2020 at 10:54:29AM +0800, Jingqi Liu wrote:
> At the end of live migration, QEMU uses msync() to flush the data to
> the backend storage. When the backend file is a character device dax,
> the pages explicitly avoid the page cache. It will return failure from 
> msync().
> The following warning is output.
> 
>     "warning: qemu_ram_msync: failed to sync memory range“
> 
> So we add 'pmem=on' to avoid calling msync(), use the QEMU command line:
> 
>     -object memory-backend-file,id=mem1,pmem=on,mem-path=/dev/dax0.0,size=4G
> 
> Signed-off-by: Jingqi Liu <jingqi.liu@intel.com>
> ---
>  docs/nvdimm.txt | 7 +++++++
>  1 file changed, 7 insertions(+)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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