From: Nick Piggin <nickpiggin@yahoo.com.au>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: linux-mm@kvack.org, "H. Peter Anvin" <hpa@zytor.com>,
Andi Kleen <ak@suse.de>,
"Eric W. Biederman" <ebiederm@xmission.com>,
akpm@linux-foundation.org, Yinghai Lu <yhlu.kernel@gmail.com>,
Chandramouli Narayanan <mouli@linux.intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm -v4 1/3] i386/x86_64 boot: setup data
Date: Tue, 9 Oct 2007 02:06:21 +1000 [thread overview]
Message-ID: <200710090206.22383.nickpiggin@yahoo.com.au> (raw)
In-Reply-To: <1191918139.9719.47.camel@caritas-dev.intel.com>
On Tuesday 09 October 2007 18:22, Huang, Ying wrote:
> On Tue, 2007-10-09 at 01:25 +1000, Nick Piggin wrote:
> > On Tuesday 09 October 2007 16:40, Huang, Ying wrote:
> > > +unsigned long copy_from_phys(void *to, unsigned long from_phys,
> > > + unsigned long n)
> > I suppose that's not unreasonable to put in mm/memory.c, although
> > it's not really considered a problem to do this kind of stuff in
> > a low level arch file...
> >
> > You have no kernel virtual mapping for the source data?
>
> On 32-bit platform such as i386. Some memory zones have no kernel
> virtual mapping (highmem region etc).
I'm just wondering whether you really need to access highmem in
boot code...
> So I think this may be useful as a
> universal way to access physical memory. But it can be more efficient to
> implement it in arch file for some arch. Should this implementation be
> used as a fall back implementation with attribute "weak"?
Definitely on most architectures it would just amount to
memcpy(dst, __va(phys), n);, right? However I don't know if
it's worth the trouble of overriding it unless there is some
non-__init user of it.
next prev parent reply other threads:[~2007-10-09 8:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-09 6:40 [PATCH -mm -v4 1/3] i386/x86_64 boot: setup data Huang, Ying
2007-10-08 15:25 ` Nick Piggin
2007-10-09 8:22 ` Huang, Ying
2007-10-08 16:06 ` Nick Piggin [this message]
2007-10-09 8:55 ` Huang, Ying
2007-10-08 16:28 ` Nick Piggin
2007-10-09 9:26 ` Huang, Ying
2007-10-09 11:44 ` Oleg Verych
2007-10-09 11:13 ` Andi Kleen
2007-10-09 14:00 ` huang ying
2007-10-09 14:04 ` Andi Kleen
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