NAME

       vga_setlinearaddressing - switch to linear addressing mode

SYNOPSIS

       #include <vga.h>

       int vga_setlinearaddressing(void);

DESCRIPTION

       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()).   The  vga_set*page(3)  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).

       Use vga_modeinfo(3) to check for availability of the function in a given mode.

       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

       nolinear
              Inhibit use of a linear mmaped frame buffer.

       linear 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.

       The testlinear(6) demo shows the use of this feature (and if it works for you).

SEE ALSO

       svgalib(7),     vgagl(7),      libvga.config(5),      testlinear(6),      vga_modeinfo(3),
       vga_getgraphmem(3),      vga_setpage(3),      vga_setreadpage(3),     vga_setwritepage(3),
       vga_setlinearaddressing(3)

AUTHOR

       This manual page was edited by Michael Weller  <eowmob@exp-math.uni-essen.de>.  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 Hanemaayer
       <H.Hanemaayer@inter.nl.net>.

       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.