[Libdlo] displaylink-mod status for kernel 2.6.18

[Alexander Todorov]

Bernie Thompson wrote:
> Hi Alexander,
> 
> Thanks for reporting this.  That problem comes up on kernels where the
> kzalloc function fails for the largish framebuffer backing allocation.
> 
Ahh,
changing this worked for me. I've tried it with the displaylink-mod-0.3.0 from
the wiki. See my report below.


> The nice thing is we have so many darn branches floating around now,
> that we have one for every occasion.  :) This branch of
> displaylink-mod (which forgoes allocating a backing bufffer entirely,
> with a tradeoff in performance) should work:
> http://git.plugable.com/gitphp/index.php?p=displaylink-mod&a=tree&h=refs/heads/noback&hb=noback
> 
> As will Jaya's displaylinkfb, or patching to use a different
> allocation function (search the list for a patch from Dan Ellis).

This patch never made it in. See below.

> 
> The udlfb 0.4.0 release yesterday, however, will still have the same
> behavior you're currently seeing on displaylink-mod 0.3.
> 
> On plans:
> 
> We need to get things moving forward with the driver that's already in
> kernel (udlfb) so we can get all this stuff in one place.  

To align with this plan I'm sending a patch against the udlfb code at
git.plugable.com. It will change the kzalloc call to vmalloc and will also
change the log message to English so it's more understandable. This is based on
older messages by Dan ([1] and [2]) but his requests never made it in or got
lost. I'm using RHEL5.4 with this patch which will most likely fix things on
CentOS and derived distros as well.

After successfully installing the driver (with patch) my monitor turns green and
is used as the primary text console. The TextConsole wiki page [3] is not
accurate for RHEL (and derived distros).

"echo 0 > /sys/class/vtconsole/vtcon1/bind" fixed things for me while on my
distro there's no fbcon module. If there's a bug it's probably Debian/Ubuntu
specific.


[1] - http://lists.freedesktop.org/archives/libdlo/2009-June/000194.html
[2] - http://lists.freedesktop.org/archives/libdlo/2009-July/000268.html
[3] - http://libdlo.freedesktop.org/wiki/TextConsole


Regards,
Alexander.
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