I edited my config.txt to add:
sdtv_aspect=3
sdtv_mode=2
hdmi_mode=4
disable_overscan=1
and this resulted in a garbage display on boot, so I removed the sdtv lines and that fixed it. They should only affect Composite and I'm using HDMI->DVI but obviously not.
However, hdmi_mode=4 which should be 1280x720@60hz according to this http://elinux.org/RPiconfig, gave an out of proportion boot screen and once XBMC had booted it was locked to 640x480. It seems from that page that it must have been using hdmi_group=2 as that does give 640x480 for hdmi_mode=4 but I can't imagine why my TV would report over the EDID that it uses this group as that doesn't include the resolutions 1280x720 or 1920x1080 that my TV uses. I didn't have to specify the group with previous builds for it to work either.
sdtv_aspect=3
sdtv_mode=2
hdmi_mode=4
disable_overscan=1
and this resulted in a garbage display on boot, so I removed the sdtv lines and that fixed it. They should only affect Composite and I'm using HDMI->DVI but obviously not.
However, hdmi_mode=4 which should be 1280x720@60hz according to this http://elinux.org/RPiconfig, gave an out of proportion boot screen and once XBMC had booted it was locked to 640x480. It seems from that page that it must have been using hdmi_group=2 as that does give 640x480 for hdmi_mode=4 but I can't imagine why my TV would report over the EDID that it uses this group as that doesn't include the resolutions 1280x720 or 1920x1080 that my TV uses. I didn't have to specify the group with previous builds for it to work either.