new x86 setup code hangs on Dell Inspiron 5150

[Will Simoneau]

While trying to put together a new kernel for my laptop (Dell I5150, as
in subject) I found that recent kernels just don't boot. Right after
grub loads the kernel, before the "Uncompressing Linux" message is
shown, it hangs. The BIOS appears to still be alive (ctrl-alt-del works,
keyboard lock LEDs respond). It seems to be caused by the new x86 setup
code.

My kernel is Linus' git as of a1c582d0720f2eff61043e90711767decf37b917.
I bisected and confirmed that 4fd06960f120e02e9abc802a09f9511c400042a5
triggers a non-functioning boot.

This system has Dell BIOS rev A38 and a P4 3.2 w/HT.

What should I do next to debug this problem?

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