Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannotboot

From: H. Peter Anvin
Date: Tue Jul 22 2008 - 09:25:26 EST

Ingo Molnar wrote:

Not a bug.

it would still be nice to get a nice printk and panic during bootup instead of some obscure crash, hm?

Yes. The fundamental problem is that Centaur has a set of CPUs which report family == 6 but don't have the long NOP instructions. We would need an exact CPUID criterion for these CPUs in order to be able to report it as an error. An alternative would be to attempt trapping in the real-mode code (#UD is one of the *very* few CPU exceptions which can be reliably captured in real mode on a BIOS system), but doing so would probably mean breaking Loadlin at the very least.

We can't "printk and panic" because we never get that far in the kernel proper, for obvious reasons: the code is quite littered with these buggers.

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