Re: Bad Illegal instruction traps on dual-Xeon (p4) Linux Dell box

Kurt Garloff (kurt@garloff.de)
Thu, 21 Mar 2002 00:26:10 +0100


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On Wed, Mar 20, 2002 at 01:35:30PM -0800, Tom Epperly wrote:
> The kernel log showed me that various standard programs such as
> /bin/sh are generating bogus illegal instruction traps on a legal
> opcode (0x55) as part of a standard function preamble. After receiving
> an illegal instruction trap on opcode (0x55), the modified kernel does
> a wbinvd() to flush the cache and a __flush_tlb() to flush the TLB
> and then retries the "illegal" opcode. The retry produces a second
> illegal instruction trap on the same legal opcode (0x55). Information
> from /var/log/messages is shown below.

The CPU is what triggers the exception.
So this sounds like a defect (or overheated) CPU to me.

OTOH, the kernel logs "invalid operand". Could you run ksymoops to get a
disassembly?
AFAICS, its a push %ebp instruction, which should not be illegal. So either
your stack is overflowing or my suspicion with the defect CPU is applicable.

Regards,
--=20
Kurt Garloff <kurt@garloff.de> [Eindhoven, NL]
Physics: Plasma simulations <K.Garloff@Phys.TUE.NL> [TU Eindhoven, NL]
Linux: SCSI, Security <garloff@suse.de> [SuSE Nuernberg, DE]
(See mail header or public key servers for PGP2 and GPG public keys.)

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