Kernel almost hangs when CONFIG_DRM_RADEON=y

[Borislav Petkov]

On Mon, Aug 29, 2011 at 11:47:24AM -0400, David Airlie wrote:
> > 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.

So it seems like all the request_firmware() drivers could use a Kbuild
functionality of some sort which presents the user with an option to
select the firmware blobs for his hw when those drivers are =y. Hairy.

Adding kbuild ML.

-- 
Regards/Gruss,
Boris.