[vbox-dev] Linux guest: two framebuffer devices? Is it possible?

Jan Petrouš jan.petrous at tieto.com
Tue Sep 6 09:22:47 GMT 2016

Hi Michael.

On 6 September 2016 at 11:13, Michael Thayer <michael.thayer at oracle.com>
> Hello Jan,
> I think you asked about this on IRC yesterday.  The first file that you
mention is part of the Linux drm driver (the rest is the other files in
that folder).  I wrote the driver, based on in-kernel ones, but I am not an
expert in the kernel drm subsystem, and in particular I only use the basic
kernel fbdev translation functions to provide the framebuffer driver.  You
would probably be better asking on the dri-devel list<1> about what to
change to get one fbdev device per head.  You might be in luck and there
might be a simple solution.

Yes, I was asking on irc, but I think I fallen in lunch mode there, so only
silence :)
That is why I asked here again.

Anyway, thanks for the hints! I definitely will have a try with drm.

But it's good that the author of driver is reachable.
So more questions can come later ;)


> Regards,
> Michael
> <1> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> On 05.09.2016 17:42, Jan Petrouš wrote:
>> Hi,
>> as VirtualBox supports dual head config I was trying to start two
>> framebuffers on it.
>> But unsucessfull.
>> The main constraint is that guest Linux is very tiny and has no
>> X-Windows inside.
>> The application requires only the framebuffer devices.
>> I did many hours googling to find solution but I found only solution for
>> xwin environment.
>> Is it even possible to enable two FB devices on dualhead configuration?
>> If the answer is NO, can you show me where I should start to look inside
>> the sources?
>> I found the VB Additions subversion repo where are at least two video
>> drivers:
>> 1,
>> 2,
>> I guess that the driver for my non-x11 environment is the first one. Is
>> it true?
>> I'm rather linux video driver noob, but I would like to get some good
>> start point
>> where I can at least try to start with.
>> BR.
>> /Jan
>> PS: Installed Fedora Server 24 Minimal config, so kernel is 4.6.7
>> _______________________________________________
>> vbox-dev mailing list
>> vbox-dev at virtualbox.org
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