[Bug 8587] New: Bug in p4-clockmod shuts Pentium 4 laptop down

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Ubuntu | linux

           Summary: Bug in p4-clockmod shuts Pentium 4 laptop down
           Product: Ubuntu
           Version: unspecified
          Platform: i386
        OS/Version: Linux
            Status: NEW
          Severity: critical
          Priority: P2
         Component: linux
        AssignedTo: fabbione at ubuntu.com
        ReportedBy: oscar at pearceenterprises.com
         QAContact: kernel-bugs at lists.ubuntu.com


I had been running Debian Sarge on this laptop for several months wityh no
problem.  Recently, I had to scrub the laptop and decided to install Hoary on
it.  What I found is that the laptop would shut off within 45-60 seconds after
logging into the desktop (which was very frustrating, I might add :-)).  It was
just like pulling the power cord out of a desktop.  Anyway, after re-installing
a minimal Sarge and then adding the same packages that ubuntu-desktop installs,
I was able to reproduce the problem after loading the p4-clockmod module and
powernowd.  Digging further, I found errata N60 in the Pentium 4 spec update
(accessible at http://download.intel.com/design/Pentium4/specupdt/24919958.pdf,
bottom of page 49).  After re-installing Hoary from scratch (again) and patching
p4-clockmod to not allow frequencies below 2.0 GHz on my processor, the system
seems to be stable.  I'll attach the patch I'm using, although it's pretty
hacky.  From the errata, it looks like processors with the following CPU IDs (as
computed by the module) are affected: 0x0f0a, 0x0f24, 0x0f27, 0x0f29, and 0x0f25.

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