Kernel almost hangs when CONFIG_DRM_RADEON=y

[David Airlie]

----- Original Message -----
> From: "Borislav Petkov" <bp at alien8.de>
> To: "Alex Deucher" <alexdeucher at gmail.com>, "Dave Airlie" <airlied at gmail.com>
> Cc: "Peter Zijlstra" <peterz at infradead.org>, "Michel Dänzer" <michel at daenzer.net>, "linux-kernel"
> <linux-kernel at vger.kernel.org>, dri-devel at lists.freedesktop.org, "Pavel Ivanov" <paivanof at gmail.com>
> Sent: Monday, 29 August, 2011 3:16:12 PM
> Subject: Re: Kernel almost hangs when CONFIG_DRM_RADEON=y
> On Mon, Aug 29, 2011 at 09:48:22AM -0400, Alex Deucher wrote:
> > >> Should we make Kconfig pop up a dialog and ask for the
> > >> whereabouts of
> > >> these firmware thingies when you mark the driver =y?
> > >>
> > >> This all sounds like magic to me, having to know you need to add
> > >> to
> > >> EXTRA_FIRMWARE, having to know what file it needs etc.. For all
> > >> intents
> > >> and purposes =y just doesn't work and that's broken.
> > >
> > > Yep, you make a lot of sense. I had to fumble the build/reboot
> > > cycle a
> > > couple of times and do some code staring even to figure this out.
> > > In
> > > the end, I copied the whole radeon/ folder from David's firmware
> > > git
> > > repo into /lib/firmware and made radeon.ko =m again so that I
> > > don't have
> > > to add *.bin entries to CONFIG_EXTRA_FIRMWARE each time I'm
> > > building a
> > > kernel on a different machine.
> > >
> > > Besides, there was this other issue on lkml today where
> > > CONFIG_EXTRA_FIRMWARE can cause nconf to segfault when you
> > > overflow
> > > its length of 256 by trying to include a bunch of firmware *bin
> > > files:
> > > http://lkml.org/lkml/2011/8/29/86
> >
> > If you are going to build the ucode into your kernel you'll need to
> > pick the ones you want to include or increase the limit regardless
> > of
> > whether it's radeon ucode or ucode for some other chip. For a
> > particular card you only need the ones for that card (e.g.,
> > CEDAR_*.bin or REDWOOD_*.bin, etc.)
> 
> Alex, Dave, yeah, that's all fine.
> 
> The question Peter asked is, how to make this much more understandable
> to the user so that she/he doesn't have to figure it out on their own.
> IOW, if one sets RADEON to =y in Kconfig, it should automatically
> generate a selection menu with all the firmware required so that
> the user can select from it either the CEDAR* or the REDWOOD* (or
> the DOUGHNUT* :-)) ones for her/his card and when the user selects
> one entry, the required strings are added to CONFIG_EXTRA_FIRMWARE
> _automatically_.
> 
> Maybe even Kbuild should try to find them on the system, and, if
> unable
> to, remind the user to install the needed firmware package.
> 
> Anyway, something to that effect, the above is just to illustrate the
> intention, I don't know whether it would work. In any case, we're
> lacking user help there and we don't want to put every user through
> the process of finding which firmware files she/he needs when setting
> RADEON=y.
> 
> Does that make more sense?

Oh it makes sense, just neither of us are Kbuild hackers and I'm not sure that'll change at any point :)

It also sounds like something that could apply to any driver with external firmware.

Dave.