C&T vga - newbie quests

[Peter Stuge]

On Thu, Jan 23, 2003 at 10:19:19PM -0500, John van Vlaaderen wrote:
> Thanks Peter, but... maybe i should have said:
> 
> ...In relation to LinuxBIOS...
> 
> We know what X and a vgabios are -- what I am asking about are 
> references on this mailing list to writing X into a vgabios -- maybe 
> VIA -- using code from the bochs vgabios -- or something like that -- 
> along w/ Xfree86

XFree86 v4 have some provisions for using a VGA BIOS.  If you have a VGA
BIOS in the system you can get XFree86 running.  (Although not at the
highest possible speed with the highest possible resolution or colour
depth.)


> Framebuffers are new to me, never really thot about them, I am looking 
> of DirectFB right now and it really seems like an acceleration process, 
> so I  am wondering why it keeps appearing in LinuxBIOS mailing lists.

Many people are used to having a standard keyboard and a monitor attached to
their computer system, a console.  Because VGA BIOSes often rely heavily on
legacy BIOS services (sorry, should've mentioned this part yesterday) these
VGA BIOSes cannot be utilized in LinuxBIOS (yet) because LinuxBIOS doesn't
provide these legacy BIOS services (interrupt services, int 15h etc.  Search
Ralph Brown's interrupt.lst for the keyword BIOS. :) yet.  There is work
underway to add needed parts from the Bochs project's GPL legacy BIOS to
LinuxBIOS, which would also allow all VGA BIOSes to work.

The VGA BIOS and the framebuffer driver serve the same purpose, to activate
the monitor connected to the graphics adapter in the system.  This is more
relevant in some cases than other.  For a GPL desktop system you'd want it. 
For a cluster node you couldn't care less.

The VGA BIOS has an advantage over the framebuffer in that it will be
initialized somewhat earlier, on the other hand I suspect that much of
LinuxBIOS's hard work will already be done when the VGA BIOS gets
initialized so LinuxBIOS debugging will still be best made through the
serial port.  The VGA BIOS is also closed source, of course, which is to
it's disadvantage.


> What is envisioned for getting X running from LinuxBIOS ??  Clusters 
> obviously have no need for them, but there are huge hungry embedded 
> people out there.  I would like to join the fray with some useful 
> information.

If all you want is X and don't care about the Linux text console, you'll
need either a VGA BIOS or a native graphics chipset driver in the X server.
If all you have is the VGA BIOS the X server will have pretty poor
performance.


> Only part of the need is being kewl, the more important issue becomes 
> getting proprietary code out of the PC completely, as dictated by the 
> GNU religion, and gaining support among the youth.

It's coming.  It's just taking some time.  The PC architecture is about 20
years worth of kludges on top of each other.


//Peter