Re: [PATCH 00/19] pramfs

[Vladimir Davydov <vdavydov@parallels.com>]

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@gmail.com> 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