[sf-lug] framebuffer console hangs...

John Magolske b79net at gmail.com
Wed Aug 20 13:49:43 PDT 2008

While in text mode in a framebuffer console, I'm having issues with
the display 'hanging'. For example, while moving the text cursor in
Vim, the cursor will sometimes freeze for 3 or 4 seconds then jump
ahead the distance it would've moved while frozen. Or while scrolling
text in Less, the text will freeze then jump ahead in the same manner.
When switching between terminals in GNU Screen there can be a several
second pause...quite annoying.

This is on a Thinkpad X40 booting and running off a 12GB CompactFlash
card (Sandisk Exteme III) using an IDE-CF adapter [1]. The distro is
Debian unstable, via the grml live-CD [2] installed to hard-disk. Not
sure if the problem is related to using a a Flash HD...I've run other
machines off CF without this issue. The X40 uses shared video memory.

Someone at Monday's JavaCat meeting suggested trying a different
video driver for the framebuffer. Here's what I have on board:

    # ddcprobe
    vbe: VESA 3.0 detected.
    oem: Intel(r)852GM/852GME/855GM/855GME Graphics Chip
         Accelerated VGA BIOS
    vendor: Intel Corporation
    product: Intel(r)852GM/852GME/855GM/855GME Graphics Controller
             Hardware Version 0.0
    memory: 8000kb
    mode: 1280x1024x256
    mode: 1280x1024x64k
    mode: 1280x1024x16m
    mode: 1024x768x256
    mode: 1024x768x64k
    mode: 1024x768x16m
    mode: 640x480x16m
    mode: 800x600x64k
    mode: 800x600x16m
    mode: 640x480x256
    mode: 800x600x256
    mode: 640x480x64k

Reading through /usr/share/doc/.../Documentation/fb/intelfb.txt.gz
led me to try this in /etc/lilo.conf :

    append="video=intelfb:mode=1024x768-24 at 60,accel,hwcursor "

Taking a look in dmesg, there doesn't seem to be any reference to
intelfb, just vesafb:

    % dmesg
    Boot video device is 0000:00:02.0
    vesafb: framebuffer at 0xe0000000, mapped to 0xe0280000,
            using 6144k, total 8000k
    vesafb: mode is 1024x768x32, linelength=4096, pages=1
    vesafb: scrolling: redraw
    vesafb: Truecolor: size=8:8:8:8, shift=24:16:8:0
    Console: switching to colour frame buffer device 128x48
    fb0: VESA VGA frame buffer device

When loading intelfb manually:

    # modprobe intelfb

there's this:

    % dmesg
    intelfb: Framebuffer driver for Intel(R)
             830M/845G/852GM/855GM/865G/915G/915GM/945G/945GM chipsets
    intelfb: Version 0.9.4
    ACPI: PCI Interrupt 0000:00:02.0[A] -> GSI 16 (level, low) -> IRQ 16
    intelfb: Cannot reserve FB region.

And the hanging display issue persists. Am I on the right track trying
to use intelfb? Is the Framebuffer video driver a likely culprit?
Could it be something else? Any suggestions regarding how to diagnose
the problem would be much appreciated.



[1] AD44MIDE2CF IDE to 2 CF slots Adapter for Notebook
    (note: only one slot is really usable...the 'slave' slot
    is realllly slow, no DMA)
[2] grml - Linux Live-CD for sysadmins / texttool-users / geeks

John Magolske

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