[GLLUG] FreeBSD console res

Adam McDougall mcdouga9@egr.msu.edu
Wed, 18 Sep 2002 12:54:03 -0400


On Mon, Sep 16, 2002 at 09:59:55PM -0400, Ben Pfaff wrote:

  "Jo Dillon" <jo@groupinfo.com> writes:
  
  > On 15 Sep 2002 at 16:55, Mike Szumlinski wrote:
  > 
  > > Does anyone know how/where to up the resolution of the console on
  > > FreeBSD?  I did a quick google with no luck.  Its currently at the
  > > default 640x480, and I'd like to kick it up to 1280x1024 or something.
  > 
  >   Hmm, so the VESA support in FreeBSD lets you change the resolution at 
  > runtime? Does anybody know why the Linux VESA framebuffer can only set 
  > the resolution once at boot? :)
  
  The Linux VESA framebuffer doesn't support calling back into the
  real-mode code after boot.  Either FreeBSD knows about a
  protected-mode interface to VESA that Linux doesn't, or it
  switches temporarily into real mode to do mode changes.  I seem
  to recall that there were experimental patches to the Linux code
  to do the latter.  I'm not sure what their fate was.

If anyone is interested in the code, I believe this is the part
you are referencing in FreeBSD.  Looks like it came about in 
Revision 1.9 of src/sys/i386/i386/vm86.c:

 Revision 1.9 / (download) - annotate - [select for diffs], Mon Mar 23
19:52:38 1998 UTC (4 years, 5 months ago) by jlemon
Add the ability to make real-mode BIOS calls from the kernel.  Currently,
everything is contained inside #ifdef VM86, so this option must be
present in the config file to use this functionality.

Thanks to Tor Egge, these changes should work on SMP machines.  However,
it may not be throughly SMP-safe.

Currently, the only BIOS calls made are memory-sizing routines at bootup,
these replace reading the RTC values.

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/i386/i386/vm86.c

And the VESA code appears to use vm86 calls:
http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/i386/isa/vesa.c?rev=1.32.6.1&content-type=text/x-cvsweb-markup



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