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Message-ID: <AANLkTimRFxKT5p1K=Rd1MxXZymonx_t6rHKBhn=8CsW=@mail.gmail.com> Date: Wed, 20 Oct 2010 12:43:21 +0800 From: Dave Young <hidave.darkstar@...il.com> To: Arnd Bergmann <arnd@...db.de> Cc: Greg KH <greg@...ah.com>, Oliver Neukum <oliver@...kum.org>, Valdis.Kletnieks@...edu, Dave Airlie <airlied@...il.com>, codalist@...emann.coda.cs.cmu.edu, ksummit-2010-discuss@...ts.linux-foundation.org, autofs@...ux.kernel.org, Jan Harkes <jaharkes@...cmu.edu>, Samuel Ortiz <samuel@...tiz.org>, Jan Kara <jack@...e.cz>, Arnaldo Carvalho de Melo <acme@...stprotocols.net>, 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>, Petr Vandrovec <vandrove@...cvut.cz>, Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>, 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 Wed, Oct 20, 2010 at 4:44 AM, Arnd Bergmann <arnd@...db.de> wrote: > On Tuesday 19 October 2010 22:29:12 Greg KH wrote: >> On Tue, Oct 19, 2010 at 09:40:47PM +0200, Oliver Neukum wrote: >> > Am Dienstag, 19. Oktober 2010, 21:37:35 schrieb Greg KH: >> > > > So no need to clean it up for multiprocessor support. >> > > > >> > > > http://download.intel.com/design/chipsets/datashts/29067602.pdf >> > > > http://www.intel.com/design/chipsets/specupdt/29069403.pdf >> > > >> > > Great, we can just drop all calls to lock_kernel() and the like in the >> > > driver and be done with it, right? >> > >> > No, >> > >> > you still need to switch off preemption. >> >> Hm, how would you do that from within a driver? > > I think this would do: > --- > drm/i810: remove SMP support and BKL > > The i810 and i815 chipsets supported by the i810 drm driver were not > officially designed for SMP operation, so the big kernel lock is > only required for kernel preemption. This disables the driver if > preemption is enabled and removes all calls to lock_kernel in it. > > If you own an Acorp 6A815EPD mainboard with a i815 chipset and > two Pentium-III sockets, and want to run recent kernels on it, > tell me about it. > > Signed-off-by: Arnd Bergmann <arnd@...db.de> > --- > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > index b755301..e071bc8 100644 > --- a/drivers/gpu/drm/Kconfig > +++ b/drivers/gpu/drm/Kconfig > @@ -73,8 +73,8 @@ source "drivers/gpu/drm/radeon/Kconfig" > > config DRM_I810 > tristate "Intel I810" > - # BKL usage in order to avoid AB-BA deadlocks, may become BROKEN_ON_SMP > - depends on DRM && AGP && AGP_INTEL && BKL > + # PREEMPT requires BKL support here, which was removed > + depends on DRM && AGP && AGP_INTEL && !PREEMPT be curious, why can't just fix the lock_kernel logic of i810? Fixing is too hard? Find a i810 hardware should be possible, even if the hardware does not support SMP, can't we test the fix with preemption? -- Regards dave -- 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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