Re:[Spam] Re: [PATCH] UML - Add a .note.SuSE section

From: Alberto Pires de Oliveira Neto
Date: Thu Aug 16 2007 - 16:57:10 EST


Hi Jeff,

I'm really sorry, but I forget to mention, that I had the same problems on a RedHat RH4 (x86_64) too.

> On Thu, Aug 16, 2007 at 09:30:56AM -0700, Arjan van de Ven wrote:
> > this sounds like something really stupid and bad... why would the kernel
> > need to have a per-distro note section???
>
> On Thu, Aug 16, 2007 at 09:39:06AM -0700, Chris Wright wrote:
> > Huh!? Why do we need a SuSE section?
>
> On Thu, Aug 16, 2007 at 09:54:55AM -0700, Greg KH wrote:
> > I agree, what did we mess up in the SuSE kernel to require such a hack?
>
> Beats the crap out of me.
>
> Drop this patch - it looks like it might just be papering over
> symptoms rather than fixing the real problem - see below.
>
> What I do know is that current UML doesn't run when built on a SuSE
> host, the UML commit which caused it to break is
> c35e584c087381aaa5f1ed40a28b978535c18fb2
>
>
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=c35e584c087381aaa5f1ed40a28b978535c18fb2;hp=a5bd1786fb30abe663b904f6d79bba413e9ba883
>
> and the difference between a working UML binary and a broken one is
> this:
>
> + 1 .note.ABI-tag 00000020 0000000060000254 0000000060000254 00000254 2**2
> + CONTENTS, ALLOC, LOAD, READONLY, DATA
> + 2 .note.SuSE 00000018 0000000060000274 0000000060000274 00000274 2**2
> + CONTENTS, ALLOC, LOAD, READONLY, DATA
>
> and the .note.SuSE section makes the difference.
>
> Looking into it a bit further, the contents of the section are:
>
> objdump --section=.note.SuSE -s uml8796-linux-good
>
> uml8796-linux-good: file format elf64-x86-64
>
> Contents of section .note.SuSE:
> 60000274 05000000 04000000 53755345 53755345 ........SuSESuSE
> 60000284 00000000 01000a02 ........
>
> which seems kind of pointless, but also harmless.
>
> The crash is in this section:
>
> __uml_setup_start = .;
> .uml.setup.init : { *(.uml.setup.init) }
> __uml_setup_end = .;
>
> with &__uml_setup_start being 8 bytes before the start of the first
> 16-byte structure in .uml.setup.init, so the structures are misaligned
> wrt the start symbol.
>
> I don't see any connection between the presence of a section at the
> start of the binary and this misalignment, so the patch is probably wrong.
>
> Jeff
>
> --
> Work email - jdike at linux dot intel dot com
>
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