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vga_setlinearaddressing(3)     Svgalib User Manual    vga_setlinearaddressing(3)

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 mem-
     ory 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  hard-
     ware  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 avail-
     able 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-es-
     sen.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 orig-
     inal  author  and	will happily accept any additions or corrections to this
     first version of the svgalib manual.

Svgalib (>= 1.2.11)		  27 July 1997	      vga_setlinearaddressing(3)

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