Odi's astoundingly incomplete notes
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[drm:r100_ring_test] *ERROR* radeon: ring test failed (scratch(0x15E4)=0xCAFEDEAD) [drm:r100_cp_init] *ERROR* radeon: cp isn't working (-22).OS-X doesn't want to boot any more. It gets stuck on an empty blue screen. Booting it in safe mode (holding down the shift key) or in single-user mode (holding command-S) works, though. Also there the cursor has the same stripy pattern.
Refit still boots and is usable, although I only get a black screen when it initializes the graphics card in "BIOS mode" most of the time. So I can control Grub only blindly, and I get no early boot messages from the kernel until the KMS driver loads.
Neat workaround for the funny barcode cursor: use the SWCursor option of the radeon driver.
Update: After a few months it got worse. With the radeon driver a lot of horizontal stripes and totally unstable. The machine would hang ever so often. Falling back to the xf86-video-modesetting driver works fine. I still get a stripy mouse cursor but at least it's stable.
Seems it's time to replace this old buddy with a new one soon.
- KSS
Hibernate (not just suspend) and resume might fix the error mentioned in the blog post.
I know it's been 10 years, but the same thing just happened to me yesterday and during investigation I stumbled upon your blog post. I was using an old Sony Vaio VGN-A317M laptop (GPU: ATI Mobility Radeon X600, OS: Xubuntu 18.04) to control a PC via RDP, when suddenly glitches appeared all over the screen, making it virtually unreadable. At first I thought the hardware was permanently damaged since the error was persistent: even the BIOS POST logo was garbled and trying to boot Windows 7 caused a BSOD. So I booted Xubuntu again, ssh'd into it and had a look at the kernel log.
This was logged when the glitches first appeared:
radeon 0000:03:00.0: ring 0 stalled for more than 10232msec
radeon 0000:03:00.0: GPU lockup (current fence id 0x000000000001932a last fence id 0x000000000001932b on ring 0)
From now on during subsequent boots the "[drm:r100_ring_test]" entries mentioned in the blog post were logged.
Then I found this bug report: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1029159
The reporter experienced the "[drm:r100_ring_test] *ERROR* radeon: ring test failed" error when resuming up from suspend. As a workaround they resumed from *hibernate* to fix it. So I gave it a try and simply running "systemctl hibernate" and resuming fixed it indeed! The glitches and error messages were gone and even Windows 7 booted again.