[Bug 53857] Weird X bug with 686 build

[jmspeex]

Public bug reported:

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

** Affects: linux-source-2.6.15 (Ubuntu)
     Importance: Untriaged
         Status: Unconfirmed

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Weird X bug with 686 build
https://launchpad.net/bugs/53857