Re: 2.6.17-mm1

From: Mel Gorman
Date: Thu Jun 22 2006 - 11:18:55 EST


On Thu, 22 Jun 2006, Franck Bui-Huu wrote:

Andrew,

Andrew Morton wrote:


All 1738 patches:

ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.17/2.6.17-mm1/patch-list


Is the following patch really needed ?

flatmem-relax-requirement-for-memory-to-start-at-pfn-0.patch

"""
The FLATMEM memory model assumes that memory is in one contigious area
based at pfn 0. If we initialise node 0 to start at any other offset we
will incorrectly map pfn's to the wrong struct page *. The key to the
memory model is the contigious nature of the memory not the location of it.
Relax the requirement for the area to start at 0.
"""

Should ARCH_PFN_OFFSET macro be used instead in order to make pfn/page
convertions work when node 0 start offset do not start at 0 ?


What happens if you have ARCH_PFN_OFFSET as

#define ARCH_PFN_OFFSET (0UL)

?

What arch is this?

My physical memory start at 0x20000000. So node 0 starts at an offset
different from 0. I setup ARCH_PFN_OFFSET this way

#define ARCH_PFN_OFFSET (0x20000000 << PAGE_SHIFT)


If physical memory starts at 0x20000000, why is the PFN not
0x20000000 >> PAGE_SHIFT ?

Until now (2.6.17), it works well, but this patch breaks my machine.

If you need more details about my memory mapping, feel free to ask.

Thanks

Franck


--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/