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From: Andrzej Jakowski <andrzej.jakowski@linux.intel.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
	Haozhong Zhang <haozhong.zhang@intel.com>,
	qemu block <qemu-block@nongnu.org>,
	Dave Gilbert <dgilbert@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	Zhang Yi <yi.z.zhang@linux.intel.com>,
	"He, Junyan" <junyan.he@intel.com>,
	kbusch@kernel.org, Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH RESEND v2] block/nvme: introduce PMR support from NVMe 1.4 spec
Date: Wed, 11 Mar 2020 15:54:31 -0700	[thread overview]
Message-ID: <12576914-0ef4-efd2-355a-cff3f4eeae69@linux.intel.com> (raw)
In-Reply-To: <CAJSP0QXatOWgicLo5sGt9KA2QupC2qXD2LCdHWKgHFdzgt9pEg@mail.gmail.com>

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?



  reply	other threads:[~2020-03-11 22:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06 22:38 [PATCH RESEND v2] block/nvme: introduce PMR support from NVMe 1.4 spec Andrzej Jakowski
2020-03-10  9:51 ` Stefan Hajnoczi
2020-03-10 20:09   ` Andrzej Jakowski
2020-03-11  9:20     ` Stefan Hajnoczi
2020-03-11 22:54       ` Andrzej Jakowski [this message]
2020-03-12  6:08         ` Klaus Birkelund Jensen
2020-03-16 11:32           ` Stefan Hajnoczi
2020-03-16 17:10             ` Andrzej Jakowski
2020-03-17 11:23               ` Stefan Hajnoczi
2020-03-18  4:20                 ` Andrzej Jakowski

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