Re: [PATCH 00/19] pramfs

From: Vladimir Davydov
Date: Sun Sep 08 2013 - 05:05:38 EST


On 09/07/2013 08:22 PM, Marco Stornelli wrote:
Il 07/09/2013 16:58, richard -rw- weinberger ha scritto:
On Sat, Sep 7, 2013 at 10:14 AM, Marco Stornelli
<marco.stornelli@xxxxxxxxx> wrote:
Hi all,

this is an attempt to include pramfs in mainline. At the moment pramfs
has been included in LTSI kernel. Since last review the code is more
or less the same but, with a really big thanks to Vladimir Davydov and
Parallels, the development of fsck has been started and we have now
the possibility to correct fs errors due to corruption. It's a "young"
tool but we are working on it. You can clone the code from our repos:

git clone git://git.code.sf.net/p/pramfs/code pramfs-code
git clone git://git.code.sf.net/p/pramfs/Tools pramfs-Tools

I'm a bit confused, what kind of non-volatile RAM is your fs targeting?
Wouldn't it make sense to use pstore like
arch/powerpc/platforms/pseries/nvram.c does?


Usually battery-backed SRAM, but actually it can be used in any piece of ram directly accessible and it provides a normal and complete fs interface. Usually I do the fs test remapping my system ram. You can find documentation here:

http://pramfs.sourceforge.net

I'd like to add that in contrast to pstore, pramfs allows storing any files in it, not only system logs. This can be of value even on machines w/o special devices like sram/nvram: one can store data that should be quickly restored after reboot in conventional ram and use kexec to boot to a new kernel. One of the use cases of this could be checkpointing time-critical services to ram (using criu.org) to be quickly restored after a kernel update providing almost zero-downtime.


Marco

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