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Message-ID: <1287491998.16971.360.camel@gandalf.stny.rr.com> Date: Tue, 19 Oct 2010 08:39:58 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Arnd Bergmann <arnd@...db.de> Cc: Dave Airlie <airlied@...il.com>, Theodore Kilgore <kilgota@...ach.math.auburn.edu>, Greg KH <greg@...ah.com>, codalist@...emann.coda.cs.cmu.edu, autofs@...ux.kernel.org, Samuel Ortiz <samuel@...tiz.org>, Jan Kara <jack@...e.cz>, Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>, Jan Harkes <jaharkes@...cmu.edu>, netdev@...r.kernel.org, Anders Larsen <al@...rsen.net>, linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, Bryan Schumaker <bjschuma@...app.com>, Christoph Hellwig <hch@...radead.org>, ksummit-2010-discuss@...ts.linux-foundation.org, Petr Vandrovec <vandrove@...cvut.cz>, Arnaldo Carvalho de Melo <acme@...stprotocols.net>, linux-fsdevel@...r.kernel.org, Evgeniy Dushistov <dushistov@...l.ru>, Ingo Molnar <mingo@...e.hu>, Andrew Hendry <andrew.hendry@...il.com>, linux-media@...r.kernel.org Subject: Re: [Ksummit-2010-discuss] [v2] Remaining BKL users, what to do On Tue, 2010-10-19 at 09:26 +0200, Arnd Bergmann wrote: > On Tuesday 19 October 2010 06:52:32 Dave Airlie wrote: > > > I might be able to find some hardware still lying around here that uses an > > > i810. Not sure unless I go hunting it. But I get the impression that if > > > the kernel is a single-CPU kernel there is not any problem anyway? Don't > > > distros offer a non-smp kernel as an installation option in case the user > > > needs it? So in reality how big a problem is this? > > > > Not anymore, which is my old point of making a fuss. Nowadays in the > > modern distro world, we supply a single kernel that can at runtime > > decide if its running on SMP or UP and rewrite the text section > > appropriately with locks etc. Its like magic, and something like > > marking drivers as BROKEN_ON_SMP at compile time is really wrong when > > what you want now is a runtime warning if someone tries to hotplug a > > CPU with a known iffy driver loaded or if someone tries to load the > > driver when we are already in SMP mode. > > We could make the driver run-time non-SMP by adding > > if (num_present_cpus() > 1) { > pr_err("i810 no longer supports SMP\n"); > return -EINVAL; > } > > to the init function. That would cover the vast majority of the > users of i810 hardware, I guess. I think we also need to cover the PREEMPT case too. But that could be a compile time check, since you can't boot a preempt kernel and make it non preempt. -- Steve -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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