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Date: Mon, 20 Dec 2010 09:19:32 -0800
Message-ID: <AANLkTikULE_Jncjs=PkARjZyxb=f+t=4J8g8LQL+L=BZ@mail.gmail.com>
Subject: Re: [concept & "good taste" review] persistent store
From: Tony Luck <tony.luck@gmail.com>
To: Huang Ying <ying.huang@intel.com>
Cc: Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
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        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@elte.hu" <mingo@elte.hu>, "greg@kroah.com" <greg@kroah.com>,
        "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
        David Miller <davem@davemloft.net>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Jim Keniston <jkenisto@linux.vnet.ibm.com>,
        Kyungmin Park <kmpark@infradead.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>
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On Sun, Dec 19, 2010 at 6:47 PM, Huang Ying <ying.huang@intel.com> wrote:
> 8KB is about 100-200 lines message, sometimes it may be not enough for
> all necessary information.  But in fact, we can use multiple ERST
> records to save one kernel message dumping. So the real limitation is
> just total storage capacity.

We can - but it will be a bit messy within my pstore + platform driver
framework (I'd have to have erst tell pstore that it could handle some
larger size, 2x or 3x the actual record size and then break a write
into pieces. Presumably re-assemble on the read side too).

It would be good to get some data from real users to see
whether this is required, or whether ~8K actually is adequate
in enough situations to allow us to keep the code simple.

If anyone with a fairly new X86 server system (up to a
couple of years old ... check to see whether it has ERST
support in BIOS with: "dmesg | grep ERST") wants to test
this, the latest code is in today's linux-next tree, tagged
as "next-20101220". (I have some hope that we might get
this together for the 2.6.38 merge window ... but if not,
then 2.6.39 would be fine too).

-Tony