From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sfi-mx-4.v28.ch3.sourceforge.com ([172.29.28.124] helo=mx.sourceforge.net) by 3yr0jf1.ch3.sourceforge.com with esmtp (Exim 4.69) (envelope-from ) id 1MGN6a-0006Nk-DI for user-mode-linux-devel@lists.sourceforge.net; Tue, 16 Jun 2009 01:04:52 +0000 Received: from [198.99.130.12] (helo=saraswathi.solana.com) by 1b2kzd1.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.69) id 1MGN6T-00052C-36 for user-mode-linux-devel@lists.sourceforge.net; Tue, 16 Jun 2009 01:04:46 +0000 Date: Mon, 15 Jun 2009 21:03:50 -0400 From: Jeff Dike Message-ID: <20090616010350.GA14840@c2.user-mode-linux.org> References: <6599ad830906111202u78bcf043nd0e6a54e7251d8d7@mail.gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <6599ad830906111202u78bcf043nd0e6a54e7251d8d7@mail.gmail.com> Subject: Re: [uml-devel] Building/runing UML in SMP mode List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: Paul Menage Cc: Benjamin Blum , user-mode-linux-devel@lists.sourceforge.net On Thu, Jun 11, 2009 at 12:02:56PM -0700, Paul Menage wrote: > For a while now (since tt mode was dropped and skas mode became the > only option?) it looks as though UML has been UP-only on x86-64. And > even though the configs appear to allow building SMP on x86-32, there > are things like the panic() call in kernel/smp.c:idle_thread() which > imply that it won't work too well in 32-bit mode either. > > For testing cgroups/cpusets changes we'd find it useful to be able to > run UML in SMP mode. Is anyone working on this, or can point us at a > list of the major things that need to be done to make SMP UML > practical? SMP has been problematic because of ptrace. Ironically, despite the horridness of tt mode, that was where SMP was easiest to do. The problem with SMP on skas0 is the need to detach a userspace process from one virtual CPU process and attach it to another whenever the associated UML process is migrated from one CPU to another. I actually had this somewhat working, but the code was a horror show, with much nastiness about ignoring the signals that are needed in order to prevent a detached process from running. Jeff -- Work email - jdike at linux dot intel dot com ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel