From: Ralf Baechle <ralf@linux-mips.org>
To: David Daney <ddaney.cavm@gmail.com>
Cc: Prem Mallappa <prem.mallappa@gmail.com>,
linux-mips <linux-mips@linux-mips.org>,
Prem Mallappa <pmallappa@caviumnetworks.com>
Subject: Re: [PATCH] MIPS: KDUMP: Fix to access non-sectioned memory
Date: Thu, 3 Oct 2013 22:16:41 +0200 [thread overview]
Message-ID: <20131003201641.GC15556@linux-mips.org> (raw)
In-Reply-To: <524DBC02.6020009@gmail.com>
On Thu, Oct 03, 2013 at 11:48:34AM -0700, David Daney wrote:
> I wonder, how does /dev/mem handle it? We should probably do what
> the mem driver does for this.
/dev/mem is converting physical address to virtual addresses using
xlate_dev_mem_ptr() which is defined as:
#define xlate_dev_mem_ptr(p) __va(p)
which obviously is suffering from similar problems as Prem's suggested
patch.
Fortunately /dev/(k)mem have pretty much gotten out of fashion ;-)
The x86 implementation of xlate_dev_mem_ptr() is based on ioremap_cache()
which may be x86-specific - but very handy in situations like this and
there might also be devices which want to be mapped cached.
I'm considering to implement it since ages. I just don't want a whole
flood of new cache modes like ioremap_uncached_accelerated() or maybe
ioremap_writeback_on_sunday_afternoons_only() ;-)
Ralf
prev parent reply other threads:[~2013-10-03 20:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-03 7:46 MIPS: KDUMP: fix for crashkernel to load from non-sectioned memory Prem Mallappa
2013-10-03 7:46 ` [PATCH] MIPS: KDUMP: Fix to access " Prem Mallappa
2013-10-03 18:29 ` Ralf Baechle
2013-10-03 18:48 ` David Daney
2013-10-03 20:16 ` Ralf Baechle [this message]
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