Date: Fri, 7 Nov 1997 12:41:49 -0800 (PST) From: Sean Eric Fagan <sef@Kithrup.COM> To: hackers@freebsd.org Subject: Re: Newest Pentium bug (fatal) Message-ID: <199711072041.MAA05816@kithrup.com> References: <3463605C.41C67EA6@whistle.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, 7 Nov 1997, Julian Elischer wrote: > On a "genuine Intel" pentium (not pentium pro) > execution of the following sequence, 0xf0 0x0f 0xc7 0xc8 > This disassembled into a "lock cmpxchg8b %eax", according to gdb. I sent a note to Robert Collins, who is the x86.org guy who pops up in the news periodically when Intel tries to hassle him. He says: Actually, I've known about it for a few months. I verified it back then. It's a real bug. The bug occurs when you do two illegal things at once: 1) use the invalid opcode cmpxchg8b EAX 2) put a lock prefix on a non-read/modify/write instruction. Both conditions are already illegal. However instead of generating an invalid opcode exception, the processor locks up. Based on a later message on the list I just saw, it looks like Intel cleared this up in newer versions of the processor.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199711072041.MAA05816>