Re: [PATCH 0/11] Merge ramoops and persistent_ram, generic pstore RAM backend

Marco Stornelli
2012-05-15T06:07:41Z

2012/5/14 Shuah Khan <shuahkhan@gmail.com>:
> On Mon, 2012-05-14 at 08:58 -0700, Greg Kroah-Hartman wrote:
>> On Fri, May 11, 2012 at 05:15:06PM -0700, Anton Vorontsov wrote:
>> > Hi all,
>> >
>> > There are currently two competing debug facilities to store kernel
>> > messages in a persistent storage: a generic pstore and Google's
>> > persistent_ram. Not so long ago (https://lkml.org/lkml/2012/3/8/252),
>> > it was decided that we should fix this situation.
>> >
>> > Recently ramoops has switched to pstore, which basically means that
>> > it became a RAM backend for the pstore framework.
>> >
>> > persistent_ram+ram_console and ramoops+pstore have almost the same
>> > features, except:
>> >
>> > 1. Ramoops doesn't support ECC. Having ECC is useful when a hardware
>> >    reset was used to bring the machine back to life (i.e. a watchdog
>> >    triggered). In such cases, RAM may be somewhat corrupt, but
>> >    usually it is restorable.
>> >
>> > 2. Pstore doesn't support logging kernel messages in run-time, it only
>> >    dumps dmesg when kernel oopses/panics. This makes pstore useless for
>> >    debugging hangs caused by HW issues or improper use of HW (e.g.
>> >    weird device inserted -> driver tried to write a reserved bits ->
>> >    SoC hanged. In that case we don't get any messages in the pstore.
>> >
>> > These patches solve the first issue, plus move things to their
>> > proper places. Patches that will fix the second issue are pending.
>>
>> I've applied the first 7 patches, as they were localized to the
>> drivers/staging/android/ directory, but in order for me to apply the
>> rest, I need acks from the respective subsystem maintainers.
>>
>> pstore developers, what do you say about these changes, are you ok with
>> them?
>
> Good to see this work get done. Anton beat me to it. :) I have been
> talking to pstore developers (Tony Luck) and ramoops maintainers (Kees
> Cook) about this re-architecture work since I first floated this idea on
> ce-android mailing list. I have been working on this rec-architecture
> focusing on the second feature "Pstore doesn't support logging kernel
> messages in run-time" and didn't get to ECC even though it is on my
> feature list to do bring ramconsole features into ramoops.
>
> Anton! Is it safe to assume you are planning to cover the second feature
> as well, in which case I can drop my plans to get this work done.
>
> -- Shuah
>>
>> thanks,
>>
>> greg k-h
>> --

My ack for ramoops patches. You can add my acked-by.

Marco