From: Matan Ziv-Av (matan@svgalib.org)
Date: Wed 11 Sep 2002 - 12:17:20 IDT
On Tue, 10 Sep 2002, Gilbert, John wrote:
> Hello,
> I have a Mobility Radeon 7500, and have found a strange bug using the VESA
> driver (it doesn't effect the R128 driver). The problem effects XFree86 as
> well. I have a program that reads vga_modeinfo->maxlogicalwidth, which
> happens to be 4088 at 1600x1200, then calls vga_setlogicalwidth with the
> value. The real (virtual) width is then 4080. Other values plugged into
> vga_setlogicalwidth seem to be chopped by 8 as well. The R128 driver seems
> to work correctly but has other problems (only 1600x1200 and 1280x1024 modes
> work on the LCD). If you use XFree86, set the mode to 1600x1200 using the
> VESA, and then change resolutions, you get a sliced up screen exactly like
> having a logicalwidth off by 8.
Does the program check the linewidth_unit element of the modeinfo
struct?
Not that it would help, since most drivers don't set this (and
maxlogicalwidth) correctly. In the case of the vesa driver it is
impossible to set those correctly, since there is no way for the bios
code to get the information to the program.
The best solution, in my opinion is to have vga_setlogicalwidth return
the width that was actually set, but this might have problems with old
programs.
> I have another problem that requires fixing afeature. I would like to be
> able to create programs that draw to the console without a mode change/frame
> buffer wipe. It looks like the code to do was in svgalib at one time (see
> vga.c lines 1698, and 1869), but it's now broken. I've tried fixing this
> myself but was not able to get it to work. It would bevery neat to be able
> to write programs that draw graphics on the screen while using vim or
> shelling around.
You can get svgalib to ignore console switches, but svgalib must set
mode before drawing, because otherwise how would it have the
infor,mation on screen resolution, color, depth, etc.?
>
> Thanks in advance for any help for the above issues.
> John Gilbert
> jgilbert@eosbiotech.com
>
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Matan Ziv-Av. matan@svgalib.org
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