Re: [PATCH 00/14] Pramfs: Persistent and protected ram filesystem

Tim Bird
2009-06-15T17:58:57Z

Marco wrote:
> Tim Bird wrote:
>> Marco wrote:
>>> This is a second attempt at mainlining Pramfs. The first attempt was
>>> back in early 2004 by MontaVista. Since then the kernel code has almost
>>> been completely rewritten. So my first item on the list was porting the
>>> code on a recent kernel version. After that I added the XIP support.
>> It's very nice to see this technology revived.
>>
>> Is the information at:
>> http://pramfs.sourceforge.net/
>> and
>> http://pramfs.sourceforge.net/pramfs-spec.html
>> still valid - particularly the latter?
>
> Yep. at 99%. I've done some modifications due to the porting and there
> will be some ones due to this review. I tried to talk with Steve
> Longerbeam to update the site but without success. I'd like to update it.
>
>> It would be very nice to see this get mainlined. I believe that
>> one of the main uses for this is to store crash information
>> over a reboot so the next kernel (not in crashing state) can have
>> a better chance of dealing with it. As such, I think
>> it's important to keep the code paths for Pramfs short, synchronous,
>> and unentangled with other kernel systems (block IO, page cache, etc.).
>>
>
> Yes, I quite agree. I think that this kind of feature would be very
> useful especially for the embedded world.

Just FYI - we have an "exception monitor" at Sony
which is used in several projects, that records application and
kernel crash information into the file system, for subsequent
(often in-field) analysis. However, the data currently gets written
to a flash filesystem and the logs sometimes get truncated or otherwise
corrupted. This seems like a perfect match for what we're trying
to do.
-- Tim

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America
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