From: Avery Pennarun <apenwarr@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: akpm@linux-foundation.org, josh@joshtriplett.org,
paulmck@linux.vnet.ibm.com, mingo@elte.hu,
a.p.zijlstra@chello.nl, fdinitto@redhat.com, hannes@cmpxchg.org,
olaf@aepfle.de, paul.gortmaker@windriver.com, tj@kernel.org,
hpa@linux.intel.com, yinghai@kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 0/5] Persist printk buffer across reboots.
Date: Tue, 13 Mar 2012 02:00:30 -0400 [thread overview]
Message-ID: <CAHqTa-3DiZhd_yoRTzp2Np0Rp=_zrfL7CbN_twu+ZZeu7f4ENg@mail.gmail.com> (raw)
In-Reply-To: <20120312.225302.488696931454771146.davem@davemloft.net>
On Tue, Mar 13, 2012 at 1:53 AM, David Miller <davem@davemloft.net> wrote:
> From: Avery Pennarun <apenwarr@gmail.com>
> Date: Tue, 13 Mar 2012 01:36:36 -0400
>
>> The last patch in this series implements a new CONFIG_PRINTK_PERSIST option
>> that, when enabled, puts the printk buffer in a well-defined memory location
>> so that we can keep appending to it after a reboot. The upshot is that,
>> even after a kernel panic or non-panic hard lockup, on the next boot
>> userspace will be able to grab the kernel messages leading up to it. It
>> could then upload the messages to a server (for example) to keep crash
>> statistics.
>
> On some platforms there are formal ways to reserve areas of memory
> such that the bootup firmware will know to not touch it on soft resets
> no matter what. For example, on Sparc there are OpenFirmware calls to
> set aside such an area of soft-reset preserved memory.
>
> I think some formal agreement with the system firmware is a lot better
> when available, and should be explicitly accomodated in these changes
> so that those of us with such facilities can very easily hook it up.
Sounds good to me. Do you have any pointers? Just use an
early_param? If we see the early_param but we can't reserve the
requested address, should we fall back to probing or disable the
PRINTK_PERSIST mode entirely?
Thanks,
Avery
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next prev parent reply other threads:[~2012-03-13 6:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 5:36 Avery Pennarun
2012-03-13 5:36 ` [PATCH 1/5] mm: bootmem: BUG() if you try to allocate bootmem too late Avery Pennarun
2012-03-13 5:36 ` [PATCH 2/5] mm: bootmem: it's okay to reserve_bootmem an invalid address Avery Pennarun
2012-03-13 5:36 ` [PATCH 3/5] mm: nobootmem: implement reserve_bootmem() in terms of memblock Avery Pennarun
2012-03-13 5:36 ` [PATCH 4/5] printk: use alloc_bootmem() instead of memblock_alloc() Avery Pennarun
2012-03-13 6:13 ` Yinghai Lu
2012-03-13 6:40 ` Avery Pennarun
2012-03-13 8:26 ` Ingo Molnar
2012-03-13 21:50 ` Yinghai Lu
2012-03-14 2:23 ` Avery Pennarun
2012-03-13 5:36 ` [PATCH 5/5] printk: CONFIG_PRINTK_PERSIST: persist printk buffer across reboots Avery Pennarun
2012-03-13 5:53 ` [PATCH 0/5] Persist " David Miller
2012-03-13 6:00 ` Avery Pennarun [this message]
2012-03-13 6:50 ` David Miller
2012-03-13 7:14 ` Avery Pennarun
2012-03-13 7:18 ` David Miller
2012-03-13 8:10 ` Avery Pennarun
2012-03-13 8:16 ` David Miller
2012-03-13 13:50 ` Peter Zijlstra
2012-03-14 1:57 ` Daniel Walker
2012-03-13 8:32 ` Stephen Boyd
2012-03-13 17:08 ` Daniel Walker
2012-03-13 22:10 ` Andrew Morton
2012-03-14 2:19 ` Daniel Walker
2012-03-15 22:10 ` Seiji Aguchi
2012-03-14 2:21 ` Avery Pennarun
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