Geode lxfb framebuffer not working

Kushal Koolwal kushalkoolwal at
Thu Jun 12 18:28:04 EDT 2008

Here is everything that you had asked for:

> Step 1 is to try a kernel from GIT HEAD.
Kernel: 2.6.25-rc5

> Step 2 is to send us the complete dmesg output.  What BIOS are you using?
See the attached file: dmesg_lx.txt
I am using General Software BIOS

> Step 3 is to send us the fbset information from a broken system
open /dev/fb0: No such file or directory

> Step 4 is to tell us what your monitor thinks it is driving (there is usually a information button that says what the current xres yres and refresh is).Kushal Koolwal
VFreq: 60.3
Pixel Clock:65.2
Monitor:ViewSonic VE510b

> Step 5 is to compile up the the MSR tools from hpa
> And connect via serial or net to the system when it is broken and
> send the value of MSR 0x4C000015.
debian :~# rdmsr 0x4C000015
debian :~# 

>Step 6 is to send the complete output of
debian:~# cat /sys/devices/pci0000:00/0000:00:01.1/resource
0x00000000e0000000 0x00000000e1ffffff 0x0000000000020200
0x00000000e2000000 0x00000000e2003fff 0x0000000000020200
0x00000000e2004000 0x00000000e2007fff 0x0000000000020200
0x00000000e2008000 0x00000000e200bfff 0x0000000000020200
0x00000000e200c000 0x00000000e200ffff 0x0000000000020200
0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 0x0000000000000002

>It sounds like your BIOS is horribly misconfigured.
That might be true however the same configuration (BIOS and Hardware) works fine on a 2.6.22 kernel.
Also the problem of "/dev/fb0 not present" kicked in when I used the GIT kernel (2.6.26-rc5 release). 
If I use the stable 2.6.25 from, I do get those green lines (during boot) and the device /dev/fb0 is present.

Not sure what is going wrong.


I do blog at


> Date: Thu, 12 Jun 2008 16:05:12 -0600
> From: jordan.crouse at
> To: kushalkoolwal at
> CC: mart.raudsepp at; linux-geode at
> Subject: Re: Geode lxfb framebuffer not working
> On 12/06/08 14:46 -0700, Kushal Koolwal wrote:
> > > Step 1 is to try a kernel from GIT HEAD.
> > I followed the instructions at and downloaded the GIT repository.
> > 
> > The kernel version that I got was 2.6.26-rc5
> > 
> > The problem with this was that lxfb did not find /dev/fb0 device and hence I was not sure if you still want the outputs that you had asked for.
> > 
> > Here is what the dmesg said:
> > [    0.000000] Kernel command line: root=/dev/hda1 ro video=lxfb:1024x768-32 at 60
> > [    0.173548] lxfb 0000:00:01.1: 16 KB of video memory at 0xe0000000
> There's your problem right there.  16KB is just flat out not enough video
> memory for any video mode.  It sounds like your BIOS is horribly
> misconfigured.
> > [    0.173679] lxfb 0000:00:01.1: could not find valid video mode
> This is because none of the modes we support even come close to fitting
> in 16Kb.
> > If would still like the full outputs of dmesg, fbset, msr-tool, sys/device/*, etc for this kernel I will attach it. If I did not used the kernel that you were expected then please let me know which kernel I should try.
> We definately need the pci resource list.  And what BIOS are you using?
> Jordan
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