Re: UML kernel failed to start betvee 2.6.8-rc8 and current git sources

Toralf Förster
2008-07-11T08:43:59Z

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At Thursday 10 July 2008 21:30:19 Jeff Dike wrote :
> On Thu, Jul 10, 2008 at 08:09:59PM +0200, Toralf Förster wrote:
> > At Thursday 10 July 2008 18:35:15 Jeff Dike wrote :
> >
> > > What's the host?
> >
> > tfoerste@n22 ~ $ uname -a
> > Linux n22 2.6.25-gentoo-r6 #4 Thu Jul 10 19:49:36 CEST 2008 i686 Intel(R) Pentium(R) M processor 1700MHz GenuineIntel GNU/Linux
> >
> > BTW, this works fine and shows only the config :
> > n22 ~ # linux-v2.6.26-rc8-227 --showconfig
> >
> > whereas this failed:
> >
> > n22 ~ # linux-v2.6.26-rc9-56 --showconfig
> > Locating the bottom of the address space ... 0x0
> > Locating the top of the address space ... 0xc0000000
>
> OK, I believe you're seeing the same bug as Uli saw here:
>
> http://marc.info/?l=linux-kernel&m=121011518003727&w=2
>
> More precise symptoms are here:
>
> http://marc.info/?l=linux-kernel&m=121011722806093&w=2
>
> I never did figure that one out. I had the same kernel version, same
> toolchain, same everything as far as I could see, and I couldn't
> reproduce it, except with a binary that he gave me.
>
> You're seeing it on i386, whereas he saw it on x86_64.
>
> The underlying problem is that somehow the UML initcalls aren't being
> run, which is why you're seeing all zeros in the register dump.
>
> If you bisect this, I bet you end up at the no-unit-at-a-time patch
> that he ended up at. And I have no idea what that has to do with
> anything.
>
You're right :

tfoerste@n22 ~/devel/linux-2.6 $ git bisect good
4f81c5350b44bcc501ab6f8a089b16d064b4d2f6 is first bad commit
commit 4f81c5350b44bcc501ab6f8a089b16d064b4d2f6
Author: Jeff Dike <jdike@addtoit.com>
Date: Mon Jul 7 13:36:56 2008 -0400

[UML] fix gcc ICEs and unresolved externs

There are various constraints on the use of unit-at-a-time:
- i386 uses no-unit-at-a-time for pre-4.0 (not 4.3)
- x86_64 uses unit-at-a-time always

...

--
MfG/Sincerely

Toralf Förster
pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3

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