I am using Dell D400 laptop as my 32bit test machine and during conferences. It has Pentium-M cpu and Intel 855GM/ICH4 chipset. And this is where problem starts…
As I like to use text console on it I wanted to get XGA (1024×768) framebuffer on it. So first try was “use intelfb”. But “video=intelfb:mode=1024×768-32@60″ or “modprobe intelfb mode=1024×768-32@60″ results in same message:
[ 1760.280291] intelfb: Framebuffer driver for Intel(R) 830M/845G/852GM/855GM/865G/915G/915GM/945G/945GM/945GME/965G/965GM chipsets [ 1760.280368] intelfb: Version 0.9.6 [ 1760.280471] intelfb: 00:02.0: Intel(R) 855GM, aperture size 128MB, stolen memory 892kB [ 1760.289927] intelfb: Non-CRT device is enabled ( LVDS port ). Disabling mode switching. [ 1760.290251] intelfb: Video mode must be programmed at boot time.
The solution is to give kernel “vga=792″ argument but it is not possible here as kernel thinks that 800×600-8 is highest available one.
OK, I can use X11 and terminal there — this works fine. But why kernel got so broken? Probably Intel developers do not test their changes on something older then i945 chipsets (and thats only because it is used in Atom based devices).
Looks like I need to do “git bisect” to check when it broke and then create some hack to get proper behaviour…
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Hmm. This was there for my 945 for as long as I remember. git log -S shows that the “Non-CRT device is enabled” is there at least since the 2.6.12-rc2 (the start of current kernel git).