Re: [uml-devel] [Bug 49277] Compile of usermode-sources-2.6.x fails

[Rob Landley <rob@landley.net>]

On Thursday 10 February 2005 09:33 pm, Blaisorblade wrote:
> > Sorry, meant UML.
> >
> > (I have a cold.)
>
> Best wishes for your health... (please, someone translate this to real
> English :-) )

Oh, it's real english.  (Or at least it seems so to someone who just burned 
french toast to charcoal due to being too dizzy to walk down the street to a 
sandwich shop.  I'm not exactly firing on all cylinders at present...)

> > So if I build 2.6.11-rc3-bk? I can fire up SKAS0 mode and run it on an
> > unmodified kernel?  If so, I'm happy to test this...  (I read Jeff Dike's
> > blog entry on SKAS0, but it didn't really have any implementation
> > details.)
>
> Well, code already exists. Get the appropriate -mm tree and apply on top of
> it the "incrementals" tree at
> http://user-mode-linux.sourceforge.net/patches.html.
>
> Give a quick read to the changelogs to get a feeling about what's actually
> needed and what won't at all compile. I guess that in this moment skas0-ldt
> is a good point to stop at.

Cool.  "Not tonight, I have a headache", but cool.

> Yes, obviously... actually, I also have made some confusion (I actually
> answered to "why UML in TT mode is built static?", not to the bug in TT
> mode).
>
> ***MARKED***
> The bug in TT mode: actually, it happens when and because UML is statically
> linked, against NPTL glibc. It does not happen on normal distros, which
> provide a LinuxThreads glibc in /lib and for static linking to be 2.4
> compatible; nor in Gentoo with nptl disabled (which was the default when I
> installed it).
>
> The problem, currently, is that there are problems (and linker assertion
> failures) probably because the linking scripts do not play well with
> the /usr/lib/libc.a sections. The error, if I recall it correctly, is
> posted in the comment #6.

Gee, Red Hat, the distro that brought us gcc 2.96, is now having ld throw 
assertion failures trying to build UML.  It's nice to see tradition 
maintained...

I can't debug this one.  I gave up on Fedora when FC2 wouldn't boot on my 
desktop because the kernel was optimized for a processor more recent than the 
machine had (brand new Via Samuel 2, basically a Pentium clone with MMX and 
3DNow).

I was a loyal Red Hat user for years, but Fedora just left me cold.  (And the 
_courage_ they've shown, yanking things like mp3 player support and xpdf...  
Obviously they're a good ally to stand up for decss someday.)

> Stuff below refers to "Why UML in TT mode is built static?"
>
> > but first
> > I want to confirm that you looked at the new 2.6 nonlinear mappings
> > support (mm/fremap.c, sys_remap_file_pages() and friends...)
>
> Hmm, I know that feature, only I don't understand how it could help
> *here*... basically, I think everything that you can do through
> remap_file_pages() can be done through mmap() / munmap() / mremap(), and
> the advantage is only for performance... and since the mappings in this
> case are created
>
> So, when and if there will be a remap_file_pages where you can also change
> protections and we'll drop all the mmap() we must create

Tried asking on linux-kernel?

Rob


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