Created attachment 97046 [details] A small snapshot from Firefox showing garbled text I'm seeing this issue on my computer with the Radeon-9500-AGP (r300) using the opensource drivers since the beginning of this year. That means that this issue may have started since version mesa-10.0.0. I'm using mesa-10.1.0 now. I've tested a Radeon-3650-AGP (r600) on the same computer for a few days and noticed the same issue. The garbled text is sometimes noticeable in the UI of the application like menus, but it is always noticeable when a lot of text is shown, for example in Firefox showing a webpage with a lot of text. In Firefox: The garbled text is not shown on all lines: some lines will have garbled text, while most other lines will show the text correct. Sometimes the text is so severily garbled that it is not readable anymore. Selecting the line with the garbled text with the mouse (as if doing a copy & paste action) will change (redraw?) the garbled text and usually correcting the garbled letters. The text is not garbled in Qt/KDE applications. This issue disappeared when in xorg.conf EXAPixmaps or RenderAccel is disabled (both are enabled by default). After doing this "fix" text will not be garbled anymore, but scrolling in Firefox (and possible other applications) is much slower/less smooth.
Does adding radeon.agpmode=-1 to the kernel command line in grub help? You can also try setting it to 1, 2, 4, or 8 to force the agpmode.
The problem I've described in the top comment, is when using agpmode=4. I somehow can not use agpmode=8. When agpmode is set to 8, the X server will not start. Loading the radeon module with modprobe is no problem, but starting the X server, for example with startx, will hang the computer. Xstart should open 3 xterm windows, but during the opening of the first xterm window the computer hanged. When setting agpmode to 1 or 2, I get this message: [drm:radeon_agp_init] *ERROR* Illegal AGP Mode: 1 (valid 4, 8), leaving at 8 So I can only set agpmode to -1. With agpmode=-1 the garbled text has disappeared. But certain movements on the screen can not keep up with the mouse movement. For example when moving around a window with the mouse (I use KDE's wobbling window) and scrolling a long webpage by dragging the vertical slider up and down with the mouse in Konqueror/Rekonq (Firefox doesn't have this problem). The movement on the screen is smooth, but it is more behind the mouse than when agpmode is set to 4. Setting agpmode to -1 is a better solution than disabeling EXAPixmaps or RenderAccel.
Today I've replaced the Radeon-9500-AGP with a Radeon-HD2400Pro-AGP. Text in Gtk2-apps are good even when using agpmode=8. No sign of garbled text. After inspection of the Radeon-9500, I see 4 bulging capacitors... so maybe that was the reason of the garbled text and the inability to use agpmode=8.
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