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From: Jeff Dike <jdike@addtoit.com>
To: Ingo Molnar <mingo@elte.hu>
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 12:22:31 -0500	[thread overview]
Message-ID: <200401201722.i0KHMWDG003192@ccure.user-mode-linux.org> (raw)
In-Reply-To: Your message of "Mon, 19 Jan 2004 09:28:05 +0100." <20040119082805.GA4412@elte.hu>

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?

> so the only compatible solution seems to be to implement set/
> get_thread_area() within UML. Since UML itself is linked statically,
> which causes the non-TLS glibc to be linked, i think it should be safe
> to just shadow the TLS descriptors in the UML process and call
> set_thread_area() for every new thread that has TLS descriptors not
> equal to the previous thread's TLS descriptors.

In tt mode, this is true.  A skas-only UML will be dynamic, but then
userspace is in a separate process, and someone was thoughtful enough to
add PTRACE_[GS]ET_THREAD_INFO.  So, this will be fine in either case.

The problem is on 2.4.  I suspect that this can't be emulated on 2.4 hosts,
so a 2.6 UML can't boot a NPTL system on a 2.4 host.  This is annoying since
host version independence is a nice thing about UML.

> but wrt. LinuxThreads - it doesnt seem UML skas mode implements LDT
> state properly - does it? 

As far as I know, it does.  LinuxThreads was introduced in RH8 or so, I think,
and RH8 filesystems have run in UML for a long time.

				Jeff



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  parent reply	other threads:[~2004-01-20 17:00 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 [this message]
2004-01-20 19:59                 ` Ingo Molnar
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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