Re: difference in maximum color depth in Debian vs Mac OS?
+----[ Brad Boyer <flar@allandria.com> (31.Jan.2005 18:43):
|
| On Mon, Jan 31, 2005 at 03:04:35PM +0100, Hans Ekbrand wrote:
| > On Sat, Jan 29, 2005 at 02:31:40AM -0300, Fernan Aguero wrote:
| > > The VRAM of this Macintosh is 1MB (expandable to 4MB I
| > > believe). However what I fail to understand is why the Mac
| > > OS is able to get a higher color depth than debian/linux on
| > > the same hardware.
[snipped]
| If you look at the code for platinumfb, it believes that 1M isn't enough
| to do 832x624 in 16 bit color. There is a formula coded in to calculate
| how much VRAM any particular mode takes. It's something like this:
|
| vres*(hres*bpp + 32) + 4096
|
| Run the numbers, and it adds up to more than 1M. I have no idea where the
| constants are from, but the 32 appears to be the difference between the
| hres and the line length in the framebuffer. I don't know enough about the
| driver to figure out anything more. Perhaps some of the people who worked
| on the code are still around to answer these questions.
|
| Brad Boyer
| flar@allandria.com
|
+----]
Well spotted. I also don't know enough about this issue. I just
wanted to know if I was the only one getting frustrated by
this this problem ...
BTW is this problem only seen on platinumb fb devices? How
is this vram check done for other devices?
Fernan
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