linux-kernel - Re: [PATCH v2] ramoops: use pstore interface

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Date:	Tue, 29 Nov 2011 09:24:49 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Chen Gong <gong.chen@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org,
	Marco Stornelli <marco.stornelli@...il.com>,
	Tony Luck <tony.luck@...il.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <greg@...ah.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2] ramoops: use pstore interface

On Mon, Nov 28, 2011 at 8:50 PM, Chen Gong <gong.chen@...ux.intel.com> wrote:
> 于 2011/11/29 4:09, Kees Cook 写道:
>>
>> Instead of using /dev/mem directly, use the common pstore infrastructure
>> to handle Oops gathering and extraction.
>>
>> Signed-off-by: Kees Cook<keescook@...omium.org>
>> ---
>> This depends on the pstore changes waiting for -next in:
>>
>> http://git.kernel.org/?p=linux/kernel/git/aegl/linux.git;a=shortlog;h=refs/heads/next
>> ---
>>  Documentation/ramoops.txt |    8 +-
>>  drivers/char/Kconfig      |    1 +
>>  drivers/char/ramoops.c    |  206
>> ++++++++++++++++++++++++++++++++++-----------
>>  3 files changed, 160 insertions(+), 55 deletions(-)
>>
>> diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt
>> index 8fb1ba7..a0b9d8e 100644
>> --- a/Documentation/ramoops.txt
>> +++ b/Documentation/ramoops.txt
>> @@ -3,7 +3,7 @@ Ramoops oops/panic logger
>>
>>  Sergiu Iordache<sergiu@...omium.org>
>>
>> -Updated: 8 August 2011
>> +Updated: 17 November 2011
>>
>>  0. Introduction
>>
>> @@ -71,6 +71,6 @@ timestamp and a new line. The dump then continues with
>> the actual data.
>>
>>  4. Reading the data
>>
>> -The dump data can be read from memory (through /dev/mem or other means).
>> -Getting the module parameters, which are needed in order to parse the
>> data, can
>> -be done through /sys/module/ramoops/parameters/* .
>> +The dump data can be read from the pstore filesystem. The format for
>> these
>> +files is "dmesg-ramoops-N", where N is the record number in memory. To
>> delete
>> +a stored record from RAM, simply unlink the respective pstore file.
>
> I think the definition of "mem_address" in the doc is not very clear. It is
> not a normal memory instead of a persistent RAM. I suggest adding more
> descriptions.
> It's better if there is a real example.

Okay. I'm not sure it's in the scope of this patch, but I can try.

Marco, do you have suggestions for how this could be enhanced?

>...
>> +       /* Only store crash dumps. */
>>        if (reason != KMSG_DUMP_OOPS&&
>>        reason != KMSG_DUMP_PANIC&&
>>        reason != KMSG_DUMP_KEXEC)
>
> As Andrew mentioned here (http://lkml.org/lkml/2011/11/28/495),
> who should take this responsibility to fix this issue when conflicting

Has the "remove KMSG_DUMP_KEXEC" patch been taken? I'm happy to drop
it from the ramoops patch. It's trivial to do so.

-Kees

-- 
Kees Cook
ChromeOS Security
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