Re: [PATCH 00/17] pramfs: persistent and protected RAM filesystem

[Marco Stornelli <marco.stornelli@gmail.com>]

Il 06/01/2011 19:22, Luck, Tony ha scritto:
>> Errata corrige: maybe I used the wrong term, I meant "volatile" instead
>> of "temporary" information, i.e. I'd like to save this info to re-read
>> it later but I don't want to store it in flash, a simple log, run-time
>> information for debug like a flight-recorder or whatever you want.
> 
> I'm puzzled by the use of "a generic piece of memory" to store "persistent"
> things (Perhaps this is made clear in the 17 parts of the patch? I haven't
> read them yet).  On x86 f/w typically clears all of memory on reset ... so
> you only get persistence if you use kexec to get from the old kernel to
> the new one.
> 
> -Tony
> 

First of all, you can find a lot of information on the web site where
there is an overview and a page with implementation details, benchmark
and so on. With "a generic piece of memory" I mean a generic memory
device directly addressable. Usually this generic device is an NVRAM, so
we have a persistent store. If you haven't got this hw you can use other
devices or the classic RAM, in this case you have a fs persistent only
over reboot. The use of this fs is mainly for embedded systems, fw can
be configured to not clear *all* the memory. Pramfs is indeed supported
by U-Boot, you can see CONFIG_PRAM in the Das U-Boot manual. x86 in this
case can be a "strange" world for this fs, but however if the user wants
it can be used without problems because there aren't neither strict arch
or hw dependency.

Marco