Re: ionice kills vanilla 2.6.0-test9 was [Re: [PATCH] cfq + iopriorities (fwd)]

From: Linus Torvalds
Date: Fri Nov 21 2003 - 18:06:30 EST



[ Trivial test input file included, and "bug-binutils" added to the CC ]

On Fri, 21 Nov 2003, Linus Torvalds wrote:
>
> Just do "gdb vmlinux" and do "disassemble system_call" to see this. It
> says something like
>
> cmp $0x448,%eax
> jae syscall_badsys
>
> and it _should_ use just 274 (0x112 rather than 0x448) on x86.
>
> Now, I wonder if this has ever worked, of which binutils version broke
> it..

Some looking around shows that it works correctly on a SuSE box with

GNU assembler version 2.13.90.0.18 (i486-suse-linux) using BFD version 2.13.90.0.18 20030121 (SuSE Linux)
GNU ld version 2.13.90.0.18 20030121 (SuSE Linux)

but is broken on RH Fedora core 1:

GNU assembler version 2.14.90.0.6 (i386-redhat-linux) using BFD version 2.14.90.0.6 20030820
GNU ld version 2.14.90.0.6 20030820

So it definitely _does_ work in some versions, and the bug appears to be
new to binutils 2.14, with 2.13 doing the right thing.

You can trivially see if with a simple assembly file like

start:
.long 1,2,3,a
a=(.-start)/4

where 2.13.90 as shipped by SuSE will get it right (and generate a list of
1,2,3,4), while 2.14.90 from Fedora core will generate 1,2,3,16.

Linus


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