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From: William Lee Irwin III <wli@holomorphy.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org
Subject: [vm 0/76] convert remap_page_range() to remap_pfn_range() vs. 2.6.9-rc2-mm3
Date: Fri, 24 Sep 2004 23:53:35 -0700	[thread overview]
Message-ID: <20040925065335.GV9106@holomorphy.com> (raw)

This series resolves a physical address overflow issue in the
remap_page_range() API by replacing it with remap_pfn_range(), which
accepts its physical address argument as a pfn, hence allowing the use
of a single-precision physical address argument without the risk of
overflow at the API boundary. The above issue has hobbled support for
various 32-bit architectures, including some embedded systems (ppc440
IIRC), caused persistent portability issues for sound drivers for
legacy systems (sparc32; unfortunately this patch alone does not fully
resolve those), and according to John Fusco's reports, made drivers for
some PCI-X hardware infeasible to port to recent ia32 PAE enterprise
systems. With this patch series applied, physical address overflows on
32-bit systems caused directly by remap_page_range() are gone forever,
and ca. 100LOC of cut-and-waste driver code are swept out of existence
alongside them.

vs. 2.6.9-rc2-mm3 and the scheduler header cleanups. The parts touching
mm.h should apply with just offsets if those aren't applied beforehand.
Successfully tested on x86-64.


-- wli

P.S.: The existing solution to the sparc32 issue was to pass a double
	precision representation of the physical address as 2 single-
	precision arguments in an API (io_remap_page_range()) whose
	argument corresponding to those two was a single single-
	precision argument on most/all other architectures. The
	sparc32-specific issue requires more work beyond these patches
	to rectify. The most apparent consequence of the API skew is
	that drivers don't compile on sparc32 when they use
	io_remap_page_range() due to passing insufficient arguments,
	or vice-versa for drivers originally written for sparc32.

             reply	other threads:[~2004-09-25  6:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-25  6:53 William Lee Irwin III [this message]
2004-09-25  6:58 ` [vm 1/76] introduce remap_pfn_range() William Lee Irwin III
2004-09-25  6:59   ` [vm 2/76] convert atyfb.c to use remap_pfn_range() William Lee Irwin III
2004-09-25  7:01     ` [vm 3/76] convert gbefb.c " William Lee Irwin III
2004-09-25  7:03       ` [vm 4/76] convert sgivwfb.c " William Lee Irwin III
2004-09-25  7:05         ` [vm 5/76] convert igafb.c " William Lee Irwin III
2004-09-25  7:08           ` [vm 6/76] convert zr36120.c " William Lee Irwin III

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