Re: 2.6.21-rc5-mm[12]: Oops on bootup in xor_see_2

Previous thread: [2.6 patch] bonding/bond_main.c: make 2 functions static by Adrian Bunk on Saturday, March 31, 2007 - 1:55 pm. (1 message)

Next thread: Linux 2.6.16.46 by Adrian Bunk on Saturday, March 31, 2007 - 2:54 pm. (1 message)
From: Neil Brown
Date: Saturday, March 31, 2007 - 2:46 pm

Them bytes that look like '00' are mostly supposed to look like 'F0' -
an x86 'noop'.

Apparently a bin-utils bug.  An alpha of OpenSUSE-10.3 was compiling
kernels like this.  I'm told it has been fixed.

What distro/gcc version/binutils version was this compiled on?

It is possible that we should change the ".align 32" in
include/asm-i386/xor.h to ".align 32, 0xf0" or similar, but my
assembler knowledge stopped growing when it reached 6809, so I'd
rather someone who knew something about it did anything that was

I think it is intentional.  I cannot say if it is correct.
The purpose is to defeat cache effects somehow.
The result of that code together with the value of BENCH_SIZE being
PAGE_SIZE is that 4 pages are allocated, and the first and last are
used.
I have no idea how any cache would treat this, but that seems to be
the intent of the code.

NeilBrown
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From: Bernhard Rosenkraenzer
Date: Tuesday, April 3, 2007 - 4:02 am

You're right -- I'm using the current Ark Linux 2007.1 experimental build 
(always the latest stuff) - the update to binutils 2.17.50.0.13 broke it, 
after upgrading binutils to 2.17.50.0.14 everything is working perfectly 
again.

Thanks
bero
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