Re: Problems booting with Kernel 2.0.36

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Wed, 16 Dec 1998 17:23:01 +0000


On Wed, Dec 16, 1998 at 11:28:48AM +0000, Riley Williams wrote:
> I'm always suspicious of problems occurring on Pentium-60 based
> systems since that was the chip with the infamous division bug. Linux
> is supposedly protected against it, but I don't know how secure that
> protection is, or whether there's not something in the boot code that
> catches it - the BogoMIPS calculation might...

Linux detects the fdiv bug, and lets you know in case your application
cares, but it doesn't fix it. This one doesn't lock up the machine,
it's just an arithmetic problem.

The bug it protects against is the f00f bug, which does lock up the
machine without the protection. This bug doesn't occur until someone
deliberately runs an f00f instruction (or some variant), so it's not
likely to affect booting.

It may be, however, that the protection code has a bug, and when it is
turned on it locks up the machine.

-- Jamie

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