Messages in this thread | | | Subject | Re: Direct access to hardware | From | Krzysztof Halasa <> | Date | 27 Jul 2000 00:05:25 +0200 |
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James Sutherland <jas88@cam.ac.uk> writes:
[FDIV errors on pentiums]
> > So what does the kernel (can) do to prevent this problem on defective > > pentiums? > > Trap the defective instructions, and implement a replacement instruction > in software. On later Intel CPUs, you can sometimes use a microcode update > to fix it - this also requires OS intervention. > > Either way, essentially you tell the OS to block the duff instructions, > and it does so.
Have you bothered to check this, or it's just a guess?
The truth is that the kernel does exactly nothing except printing warning message about defective FPU. It's up to the application to deal with the problem. Yes, it would be possible for the kernel to check all executed instructions - guess why it doesn't do that?
The bug is only present on some non-MMX Pentium CPUs, they have no updatable (nor downloadable) microcode. -- Krzysztof Halasa Network Administrator
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