Messages in this thread | | | Date | Tue, 26 Aug 2003 11:50:44 -0400 | From | Arvind Sankar <> | Subject | Re: vesafb mtrr setup question |
| |
On Tue, Aug 26, 2003 at 04:42:23PM +0100, Alan Cox wrote: > On Llu, 2003-08-25 at 20:43, Arvind Sankar wrote: > > In the first place, the power of two computation computes the largest > > power of 2 that is _smaller_ than video_size, so it looks like an > > off-by-1 bug. > > Not a bug - we don't know what lives above it so we can't extend the > mtrr safely > Ah. On a side not, could you drop a quick hint as to how screen_info.lfb_size is obtained?
In older (or just different?) versions of vesafb, the video_size was actually computed by multiplying xres, yres, and the bpp.
> > > /* Try and find a power of two to add */ > > > while (temp_size && mtrr_add(video_base, temp_size, MTRR_TYPE_WRCOMB, 1)==-EINVAL) { > > > temp_size >>= 1; > > > } > > > } > > > > Secondly, what's the point of requesting a smaller write-combining > > segment that won't cover all the video memory being used? > > Generally we don't use all the videoram. Its a heuristic rather than > perfection. You might want to play with improvements >
I thought the yres_virtual was computed based on how much video_ram was being used, so all of it _is_ being used, for scrollback?
-- arvind - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |