Fedora 16 black screen with Radeon HD 6470M: partially solved?

[M. Fioretti]

Greetings,

SHORT VERSION: I think I've found a temporary solution to this Fedora
install problem (found on other distros too), but I am not sure about
_why_ it works, and it's the best solution. Any feedback is very
appreciated.

I've got a HP G6 1273SL laptop with this chipset and a live cd of
Fedora 16 x86_64, KDE spin. 

When running live from the CD there were NO graphic problems.  So I
went and installed it on the laptop hard disk. The install was
successful, or so anaconda said, so I rebooted.

I got the GRUB 2 menu just fine. However, when I select or let start
the default entry, the screen goes completely black. If I remove the
"quiet" option in the grub entry I see that the last thing before it
goes black is "radeon something..." (too fast to read it...)

So it seems to me that is the same issue mentioned here:

http://ask.fedoraproject.org/question/179/black-screen-while-startingwhen...

I have done a bit of research and found this:

http://askubuntu.com/questions/28848/what-does-the-kernel-boot-parameter-...

linked from

https://answers.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+ques...

which also mentions the same problem on Fedora, and indeed, if I
enter "e" in grub and add to its initrd line the two parameters

acpi_osi=Linux acpi_backlight=vendor

Fedora boots without problems, but the laptop is quite warm.

This other page says even the first parameter alone is OK:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/765438/comments/2

Now the questions:

1) first of all, I admit I don't really understand how and why this
   works, that is if this is a real/ complete / best solution. Should
   I add those two parameters to GRUB_CMDLINE_LINUX_DEFAULT, rerun

     	 grub2-mkconfig -o /boot/grub2/grub.cfg

   and go on? I believe i should also try some combination of
   vgaswitcheroo and/or radeon.modeset=0 as mentioned in other "
   Radeon HD 6470M and black linux screen" threads like

   http://ubuntuforums.org/showthread.php?p=11271523
   http://ubuntuforums.org/showthread.php?t=1781662

   that, as far as I undertsand, should be better since they should
   completely turn off that chip and make the laptop cooler but... how
   to implement them in Fedora? This not clear to me.

2) why there was no problem with the live cd???  What are the options
   used there that make the distro work from the cd but not from the
   hard disk?

Please note that, for me, at least for the short/medium term, it is
perfectly OK for me to use only the on-board graphich chipset instead
of the radeon one, I don't need to do heavy 3D stuff with this
laptop...

	Thanks, hope this helps.

	Marco

[David G. Miller (aka DaveAtFraud)]

M. Fioretti <mfioretti <at> nexaima.net> writes:

>  
>  On Thu, Dec 08, 2011 20:18:21 PM +0100, Marco Fioretti wrote:
>  
>  > I've got a HP G6 1273SL laptop with this chipset and a live cd of
>  > Fedora 16 x86_64, KDE spin... when I [boot] the screen goes
>  > completely black.
>  > 
>  > if I... add to its initrd line the two parameters
>  >
>  > acpi_osi=Linux acpi_backlight=vendor
>  > 
>  > Fedora boots without problems, but the laptop is quite warm.
>  
>  If I check the graphich chips status, I get:
>  
>  #> cat  /sys/kernel/debug/vgaswitcheroo/switch
>  0:IGD:+:Pwr:0000:00:02.0
>  1:DIS: :Pwr: etc etc...
>  
>  so, if I understand correctly, I MUST also disable the discrete
>  graphic chip with a script like this:
>  
>  #####################################################
>  #! /bin/bash
>  
>  modprobe radeon
>  echo IGD > /sys/kernel/debug/vgaswitcheroo/switch
>  echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
>  #####################################################
>  
>  and then add to /etc/rc/rc.local
>  Is this 
>   
Same problem with this video hardware:

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core
Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA
controller])
        Subsystem: Hewlett-Packard Company Device 1671
        Flags: bus master, fast devsel, latency 0, IRQ 41
        Memory at c0000000 (64-bit, non-prefetchable) [size=4M]
        Memory at b0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at 4000 [size=64]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: <access denied>
        Kernel driver in use: i915
        Kernel modules: i915

and responded to the same kernel parameter fix.  Thanks.  I encountered this on
a HP Pavilion gz-1279dx.

The next interesting question is this.  My Fedora installation is VERY portable.
 I have it installed on an external USB drive.  This way I keep my environment
with me whether I'm at work, working from home or working someplace else.  I
just plug in the external drive and boot the system to my FC16 installation. 
So, the question is, will adding the kernel parameters mess with my ability to
boot on systems that don't require them?

Cheers,
Dave

[Michael Schwendt]

On Thu, 8 Dec 2011 20:18:21 +0100, MF (M.) wrote:

>  I got the GRUB 2 menu just fine. However, when I select or let start
>  the default entry, the screen goes completely black. If I remove the
>  "quiet" option in the grub entry I see that the last thing before it
>  goes black is "radeon something..." (too fast to read it...) 
I've tried to discuss a similar problem several times during F16
development, with a few late tips on debugging it (which have been
fruitless so far, however).

My bug report is: https://bugzilla.redhat.com/749250

My work-around is to either boot without "rhgb" or with Plymouth theme
"details". In both cases, nothing leads to a black screen.

[M. Fioretti]

On Thu, Dec 08, 2011 20:18:21 PM +0100, Marco Fioretti wrote:

>  I've got a HP G6 1273SL laptop with this chipset and a live cd
> of
>  Fedora 16 x86_64, KDE spin... when I [boot] the screen goes
>  completely black.
>  
>  if I... add to its initrd line the two parameters
>
>  acpi_osi=Linux acpi_backlight=vendor
>  
>  Fedora boots without problems, but the laptop is quite warm. 
If I check the graphich chips status, I get:

#> cat  /sys/kernel/debug/vgaswitcheroo/switch
0:IGD:+:Pwr:0000:00:02.0
1:DIS: :Pwr: etc etc...

so, if I understand correctly, I MUST also disable the discrete
graphic chip with a script like this:

#####################################################
#! /bin/bash

modprobe radeon
echo IGD > /sys/kernel/debug/vgaswitcheroo/switch
echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
#####################################################

and then add to /etc/rc/rc.local
Is this