vga_setlinearaddressing - switch to linear addressing mode
Switch to linear addressing mode. This maps all (or most) of the SVGA memory at
the position returned by vga_getgraphmem
(3) (which will probably change
by the call to vga_setlinearaddressing()).
calls are no longer required. This ensures optimal performance, however the
drawing functions of svgalib do not support this memory layout and not all
cards support it (and not in all modes).
(3) to check for availability of the function in a given
Furthermore, some cards (Cirrus) just enable this buffer at a fixed hardware
address. For Cirrus it is mapped at 14MB so you should never used it if you
have more than 14MB of memory (But how does an application know?). The Mach32
support for this is smarter. It makes this feature only available when it is
safe to be used.
To avoid all this problems you can use
- Inhibit use of a linear mmaped frame buffer.
- Allow (not enforce!) use of a linear mmaped frame buffer.
in the /etc/vga/libvga.config
file to disable the linear frame buffer if
it cannot be used.
Returns the size of the mapped framebuffer if successful (can be less than total
video memory), -1 if not.
(6) demo shows the use of this feature (and if it works for
This manual page was edited by Michael Weller
<firstname.lastname@example.org>. The exact source of the referenced
function as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm
Occasionally this might be wrong. I hereby asked to be excused by the original
author and will happily accept any additions or corrections to this first
version of the svgalib manual.