Re: [PATCH RESEND v2] block/nvme: introduce PMR support from NVMe 1.4 spec

[Andrzej Jakowski]

On 3/11/20 2:20 AM, Stefan Hajnoczi wrote:
> Please try:
> 
>   $ git grep pmem
> 
> backends/hostmem-file.c is the backend that can be used and the
> pmem_persist() API can be used to flush writes.

I've reworked this patch into hostmem-file type of backend.
>From simple tests in virtual machine: writing to PMR region
and then reading from it after VM power cycle I have observed that
there is no persistency.

I guess that persistent behavior can be achieved if memory backend file
resides on actual persistent memory in VMM. I haven't found mechanism to
persist memory backend file when it resides in the file system on block
storage. My original mmap + msync based solution worked well there.
I believe that main problem with mmap was with "ifdef _WIN32" that made it 
platform specific and w/o it patchew CI complained. 
Is there a way that I could rework mmap + msync solution so it would fit
into qemu design?