[uml-devel] Re: tt mode tls/glibc crash with 2.6 (Was: Re: uml-patch-2.6.0)

From: Ingo Molnar <mingo@elte.hu>
To: M A Young <m.a.young@durham.ac.uk>
Cc: Jeff Dike <jdike@addtoit.com>,
	user-mode-linux-devel@lists.sourceforge.net,
	Gerd Knorr <kraxel@bytesex.org>
Subject: [uml-devel] Re: tt mode tls/glibc crash with 2.6 (Was: Re: uml-patch-2.6.0)
Date: Thu, 5 Feb 2004 20:15:58 +0100	[thread overview]
Message-ID: <20040205191558.GA6580@elte.hu> (raw)
In-Reply-To: <20040205183624.GA5236@elte.hu>

* Ingo Molnar <mingo@elte.hu> wrote:

> mind sending the archparam-i386.h diff you have? I commented out the
> creation of the two vsyscall auxiliary entries in ARCH_DLINFO - is
> that enough? 

the crash here seems to be that after fork() the contents of GS are lost
and the next %gs access segfaults due to the #GPF. (which UML mistakes
for a pagefault and thus gets into an infinite loop.)

if i boot in via init=/bin/bash and do eg a 'exec /bin/ls' then this
crash doesnt happen, so it's clearly fork() somehow not inheriting the
LDT setup properly. (which could very well be due to my LDT hackery in
the 2.6 host-skas3 patch.)

while glibc seems to be innocent, this is clearly triggered by the TLS
code in glibc. Older glibc works fine.

tt mode seems to work on the other hand - and it doesnt use the LDT op
in /proc/mm. So newer host-skas3 is apparently broken to a certain
degree.

	Ingo

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