linux-kernel - Re: [RESEND][PATCH v4 0/7] efi_pstore: multiple event logging support

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Message-ID: <CAGTjWtBvFvx2A9FFpDw+18p_58JiX=zpqHAd0T=JS=r8YkZHiw@mail.gmail.com>
Date:	Fri, 2 Nov 2012 17:03:32 -0700
From:	Mike Waychison <mikew@...gle.com>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
	"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: Re: [RESEND][PATCH v4 0/7] efi_pstore: multiple event logging support

Series Acked-by: Mike Waychison <mikew@...gle.com>

Tony: Did you want to pull this?

On Thu, Nov 1, 2012 at 3:59 PM, Seiji Aguchi <seiji.aguchi@....com> wrote:
> Changelog
>
> v3 -> v4
>    - Rebase to 3.7-rc3
>    - Add ctime to an argument of efi_pstore_erase to build successfully
>      in case where CONFIG_PTORE=n is specified. (Patch 4/7)
>    - Add count to an argument of efi_pstore_erase and efi_pstore_write to
>      build successfully in case where CONFIG_PTORE=n is specified (Patch 5/7)
>    - Fix a white space damage (Patch 6/7)
>    - Modify a logic checking a 3-variable format of a variable name (Patch 7/7)
>
> v2 -> v3
>    - Create patches 6/7 and 7/7 to work with an existing format of variable name
>
> v1 -> v2
>    - Separate into 5 patches in accordance with Mike's comment
>    - Erase an extra line of comment in patch 1/5
>
> [Issue]
>
>     Currently, efi_pstore driver simply overwrites existing panic messages in NVRAM.
>     So, in the following scenario, we will lose 1st panic messages.
>
>     1. kernel panics.
>     2. efi_pstore is kicked and writes panic messages to NVRAM.
>     3. system reboots.
>     4. kernel panics again before a user checks the 1st panic messages in NVRAM.
>
> [Solution]
>
>    Solutions of this problem has been discussed among Tony, Matthew, Don, Mike and me.
>
>    http://marc.info/?l=linux-kernel&m=134273270704586&w=2
>
>    And there are two possible solutions right now.
>      - First one is introducing some policy overwriting existing logs.
>      - Second one is simply holding multiple log without overwriting any entries.
>
>    We haven't decided the overwriting policy which is reasonable to all users yet.
>    But I believe we agree that just holding multiple logs is a reasonable way.
>
>    We may need further discussions to find the possibility of introducing overwriting
>    policy, especially getting critical messages in multiple oops case.
>    But I would like to begin with a simple and reasonable way to everyone.
>    So, this patch takes an approach just holding multiple logs.
>
> [Patch Description]
>
> Seiji Aguchi (7):
>   efi_pstore: Check remaining space with QueryVariableInfo() before
>     writing data
>   efi_pstore: Add a logic erasing entries to an erase callback
>   efi_pstore: Remove a logic erasing entries from a write callback to
>     hold multiple logs
>   efi_pstore: Add ctime to argument of erase callback
>   efi_pstore: Add a sequence counter to a variable name
>   efi_pstore: Add a format check for an existing variable name at
>     reading time
>   Add a format check for an existing variable name at erasing time
>
>  drivers/acpi/apei/erst.c   |   16 ++--
>  drivers/firmware/efivars.c |  163 ++++++++++++++++++++++++++++++-------------
>  fs/pstore/inode.c          |    7 ++-
>  fs/pstore/internal.h       |    2 +-
>  fs/pstore/platform.c       |   11 ++--
>  fs/pstore/ram.c            |    9 +--
>  include/linux/efi.h        |    1 +
>  include/linux/pstore.h     |    6 +-
>  8 files changed, 143 insertions(+), 72 deletions(-)
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