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From: Ingo Molnar <mingo@elte.hu>
To: Jeff Dike <jdike@addtoit.com>
Cc: Gerd Knorr <kraxel@bytesex.org>,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] Re: uml-patch-2.6.0
Date: Tue, 20 Jan 2004 20:59:22 +0100	[thread overview]
Message-ID: <20040120195922.GA2022@elte.hu> (raw)
In-Reply-To: <200401201722.i0KHMWDG003192@ccure.user-mode-linux.org>


* Jeff Dike <jdike@addtoit.com> wrote:

> mingo@elte.hu said:
> > unfortunately, this is only the case if the kernel is below 2.5.69 and
> > has 'nptl' in the uname. Otherwise ld.so assumes full NPTL support.
> 
> So, it uses uname to figure out if the kernel has NPTL support?

yes. It goes roughly like this: if the kernel is a 2.4 one and the uname
string [extraversion] includes 'nptl' [and the first 'n' letter has to
be nptl's 'n' ...] then ld.so will try the TLS glibc. On 2.6 kernels,
glibc assumes that all the NPTL functionality is available. [the precise
rules are in the ld.so patches that Fedora's glibc srpm has.]

basically the goal was to 1) be able to boot stock 2.4 kernels and have
NPTL disabled, 2) be able to boot stock 2.6 kernels and have NPTL
enabled, 3) boot 2.4 kernels with the NPTL backport and have NPTL
enabled. (there are also tons of other checks in glibc itself that
selects between various versions of syscalls, eg. modify_ldt has
variants too. LD_ASSUME_KERNEL is taken into account as well.) It's not
simple.

(There was a failed attempt to get API versioning into the kernel to
clean up such interactions - but nothing really good was written so we
stuck with the above mechanism.)

	Ingo


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  reply	other threads:[~2004-01-20 19:58 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-01-13  5:05 uml-patch-2.6.0 Jeff Dike
2004-01-13  5:05 ` [uml-devel] uml-patch-2.6.0 Jeff Dike
2004-01-13  5:18 ` uml-patch-2.6.0 Jeff Dike
2004-01-13  5:18   ` [uml-devel] uml-patch-2.6.0 Jeff Dike
2004-01-13 10:19 ` uml-patch-2.6.0 Sven Köhler
2004-01-13 10:19   ` [uml-devel] uml-patch-2.6.0 Sven Köhler
2004-01-13 18:55   ` Gerd Knorr
2004-01-16  2:33     ` Jeff Dike
2004-01-16 10:03       ` M A Young
2004-01-16 11:42         ` Gerd Knorr
2004-01-17 16:10           ` BlaisorBlade
2004-01-16 17:27         ` Jeff Dike
2004-01-16 21:56           ` Gerd Knorr
2004-01-17 21:12           ` M A Young
2004-01-18  4:47             ` Jeff Dike
2004-01-16 23:47       ` Sven Köhler
2004-01-17 19:09       ` BlaisorBlade
2004-01-17 19:50         ` Jeff Dike
2004-01-17 20:03           ` BlaisorBlade
2004-01-18  4:51             ` Jeff Dike
2004-01-18 16:21       ` Ingo Molnar
2004-01-18 21:06         ` [uml-devel] uml 2.6.1 kbuild simplifications Ingo Molnar
2004-01-19  0:08           ` [uml-devel] " Jeff Dike
2004-01-19  7:34             ` Ingo Molnar
2004-01-20 17:40               ` Jeff Dike
2004-01-18 23:57         ` [uml-devel] Re: uml-patch-2.6.0 Jeff Dike
2004-01-19  7:53           ` Ingo Molnar
2004-01-19  8:28             ` Ingo Molnar
2004-01-20  0:19               ` M A Young
2004-01-20  0:23                 ` Ingo Molnar
2004-01-20  0:41                   ` M A Young
2004-01-23 21:52                   ` [uml-devel] tt mode tls/glibc crash with 2.6 (Was: Re: uml-patch-2.6.0) M A Young
2004-01-23 23:52                     ` [uml-devel] " M A Young
2004-01-24 12:25                       ` M A Young
2004-01-24 18:20                         ` Jeff Dike
2004-01-24 19:31                           ` M A Young
2004-01-28 11:35                             ` Ingo Molnar
2004-02-05 12:30                             ` Ingo Molnar
2004-02-05 12:45                               ` M A Young
2004-02-05 13:13                                 ` Ingo Molnar
2004-02-05 13:28                                   ` M A Young
2004-02-05 18:36                                 ` Ingo Molnar
2004-02-05 19:15                                   ` M A Young
2004-02-05 19:22                                     ` Ingo Molnar
2004-02-05 19:15                                   ` Ingo Molnar
2004-02-05 19:50                                     ` Ingo Molnar
2004-02-06  7:42                                       ` Ingo Molnar
2004-01-20  1:27                 ` [uml-devel] Re: uml-patch-2.6.0 Jeff Dike
2004-01-20 17:22               ` Jeff Dike
2004-01-20 19:59                 ` Ingo Molnar [this message]
2004-01-17 19:09 ` [uml-devel] uml-patch-2.6.0 BlaisorBlade
2004-01-17 19:51   ` Jeff Dike
2004-01-18 13:49     ` Ingo Molnar
2004-01-18 13:58       ` [uml-devel] uml-patch-2.6.1-1: VFS: Cannot open root device "ubd0" or unknown-block(0, 0) Ingo Molnar
2004-01-18 14:04         ` [uml-devel] " Ingo Molnar
2004-01-18 23:48           ` Jeff Dike
2004-01-17 20:32   ` [uml-devel] uml-patch-2.6.0 M A Young
2004-01-19 17:06   ` [uml-devel] uml-patch-2.6.0 Gerd Knorr
2004-01-20 19:42     ` BlaisorBlade
2004-01-20 21:30       ` Gerd Knorr
2004-01-18 18:46 M A Young

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