From: David Miller <davem@davemloft.net>
To: apenwarr@gmail.com
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: Mon, 12 Mar 2012 23:50:02 -0700 (PDT) [thread overview]
Message-ID: <20120312.235002.344576347742686103.davem@davemloft.net> (raw)
In-Reply-To: <CAHqTa-3DiZhd_yoRTzp2Np0Rp=_zrfL7CbN_twu+ZZeu7f4ENg@mail.gmail.com>
From: Avery Pennarun <apenwarr@gmail.com>
Date: Tue, 13 Mar 2012 02:00:30 -0400
> 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?
The interface is prom_retain() in f.e. arch/sparc/prom/misc_64.c
You give it a string name, a size in bytes, and an alignment. And you
are given a physical address on success. I'm pretty sure the string
name you give is one of the keys it uses to look up the same piece of
memory for you next time. So you can have retained memory across soft
resets not just for log buffers, but for other things too.
The idea is that you call prom_retain() before you take a look at what
physical memory is available in the kernel, and the firmware takes
this physical chunk out of those available memory lists upon
prom_retain() success.
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next prev parent reply other threads:[~2012-03-13 6:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 5:36 [PATCH 0/5] Persist printk buffer across reboots 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
2012-03-13 6:50 ` David Miller [this message]
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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