On Wed, Aug 25, 2010 at 01:29:29PM -0700, Kevin O'Gorman wrote > There are some confusing things about this. > - The log contains 1920x1080 modelines, but is not using them or > clearly stating the reason. > - The log contains the lines > (!!) MACH64(0): Virtual resolutions will be limited to 8191 kB > due to linear aperture size and/or placement of hardware cursor > image area.
1920x1080 uses how many pixels? $ echo $(( 1920 * 1080 )) 2073600 The programmers writing X drivers use ***FOUR*** bytes per pixel for 24-bit colour. This is due to double-word addressing being *MUCH* easier and faster than sliding groups of 3 bytes per pixel. This means that to support 1920x1080 at 24 bits requires how many Kbytes... $ echo $(( 1920 * 1080 * 4 / 1024 )) 8100 It'll just barely squeeze in a 1920x1080 image, but forget about acceleration or backing store, because there's almost no spare memory. What you might want to try is forcing 16-bit colour, which would use half the memory. See http://www.gentoo.org/doc/en/xorg-config.xml The magic option is DefaultDepth. You would want something like so, the identifiers changed to match your setup... Section "Screen" Identifier "Default Screen" Device "RadeonHD 4550" Monitor "Generic Monitor" DefaultDepth 16 # Skipping some text to improve readability SubSection "Display" Depth 16 Modes "1920x1080" EndSubSection EndSection When viewing hi-res colour images, you may see some banding due to the limited colourspace (64 K colours instead of 16 million), but it may offer full pixel resolution, and the banding may not be noticable most of the time. -- Walter Dnes <waltd...@waltdnes.org>
