With 2.6.9-9.EL, the kernel crashes on boot with hyperthreading turned on. With HT off, it boots fine. This happens on both x86_64 and ia32 (on the same hardware, a dual 3.4 GHz Xeon). The same machine boots with 5.0.5.EL perfectly. On x86_64, it gives the following errors: ACPI-0292: *** Error: Looking up [_PCT] in namespace, AE_ALREADY_EXISTS ACPI-1133: *** Error: [NULL NAME], AE_ALREADY_EXISTS and then oopses with a NULL pointer dereference in acpi_ps_parse_aml.
This is a known BIOS issue. Same as this one.. http://bugme.osdl.org/show_bug.cgi?id=3147 I have seen this fixed in BIOS in various platforms. Can you make sure you are running the latest BIOS. What platform is this? -Venki
These boxes are EM64T capable, but the problem happens in both 64 and 32-bit modes. These are prerelease systems on loan from Intel, so an old BIOS wouldn't be surprising. I'll try to a find out an update through partner channels and let you know the results.
BIOS update the did trick. Resolving accordingly.