Weird X bug with 686 build

[jmspeex]

Binary package hint: linux-image-2.6.15-26-686

I just discovered a very strange bug in the 686 kernel build. If I boot that kernel, the X server ends up eating about 50% CPU, even when idle. This slows down the machine dramatically. What's even stranger is that, while "top" reports that the total "user CPU%" is around 50%, all the processes it shows are using almost no CPU time. However, if I use htop instead, then I see X using all that CPU. If I run the 386 kernel, everything is fine. The problem is 100% reproducible (as soon as I boot) on the 686 kernel. My setup is:

Ubuntu Dapper
Dell D600 laptop
Pentium-M 2.13 GHz / 1 GB RAM
ATI video card (X.org reports "Chipset ATI Radeon Mobility X600 (M24) 3150 (PCIE)")
Using the open-source "ati" driver
Kernel is *NOT* tainted

[Jérôme Guelfucci (jerome-guelfucci-deactivatedaccount)]

Thank you for your bug report. Do you still have this issue with the latest release of Ubuntu ? (I will try to triage all your unconfirmed bugs)

[jmspeex (jean-marc-valin)]

Upgraded Ubuntu twice (to Feisty) and changed machine (to a 64-bit one) in the mean time, so I'm no longer affected by this Dapper/i386 bug.

[Jérôme Guelfucci (jerome-guelfucci-deactivatedaccount)]

Ok thank you, I'm closing this.