Comment 25 for bug 1049630

I have a packard bell dot m/a (radeon x1270) and have the issue described in this bug. My setup:
 * kernel 3.2
 * libdrm 2.4.30
 * mesa 7.11.2

I replaced the bios with a modded one that allow tweaking of video ram type. I tried two settings: uma only and uma+sideport.

 * UMA (256M)
   * No graphic corruption
   * No laggy window movement
   * glxgear fps ~= 360

 * UMA+sideport (256M+64M)
   * Massive graphic corruption
   * Laggy window movement
   * glxgears fps ~= 200

A diff between dmesg output:
$ diff dmesg.uma dmesg.uma+sideport
9c9
< [drm] Detected VRAM RAM=256M, BAR=256M
---
> [drm] Detected VRAM RAM=384M, BAR=256M
11c11
< [drm] radeon: 256M of VRAM memory ready
---
> [drm] radeon: 384M of VRAM memory ready
15c15
< [drm] PCIE GART of 512M enabled (table at 0x000000006C180000).
---
> [drm] PCIE GART of 512M enabled (table at 0x000000006B800000).
31a32
> [drm] radeon: power management initialized

Hope it can help. I can make more test if needed.