From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.12] helo=sc8-sf-mx2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1Aj21J-0005OS-9d for user-mode-linux-devel@lists.sourceforge.net; Tue, 20 Jan 2004 11:58:41 -0800 Received: from mx1.elte.hu ([157.181.1.137]) by sc8-sf-mx2.sourceforge.net with esmtp (Exim 4.30) id 1Aj21I-0002i2-SR for user-mode-linux-devel@lists.sourceforge.net; Tue, 20 Jan 2004 11:58:41 -0800 From: Ingo Molnar Subject: Re: [uml-devel] Re: uml-patch-2.6.0 Message-ID: <20040120195922.GA2022@elte.hu> References: <200401130505.i0D55XS4026774@ccure.user-mode-linux.org> <87y8sbbrup.fsf@bytesex.org> <200401160233.i0G2Xcrf004288@ccure.user-mode-linux.org> <20040118162112.GA15509@elte.hu> <20040118235730.GC21046@ccure.user-mode-linux.org> <20040119075351.GA4088@elte.hu> <20040119082805.GA4412@elte.hu> <200401201722.i0KHMWDG003192@ccure.user-mode-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200401201722.i0KHMWDG003192@ccure.user-mode-linux.org> Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Tue, 20 Jan 2004 20:59:22 +0100 To: Jeff Dike Cc: Gerd Knorr , user-mode-linux-devel@lists.sourceforge.net * Jeff Dike 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 ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel