Messages in this thread |  | | From | Praveen Dwivedi <> | Subject | Re: This can freeze linux 2.0 on 486 | Date | Thu, 30 Jan 1997 11:29:21 -0800 (PST) |
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> > > Recently I saw this behaviour on linux 2.0 running on i486. > > Instruction invd ( supposed to invalidate cache) can lock the m/c > > completely. > Alan Cox writes -
> If you can do this from userspace can you try the same with a different > OS on the same hardware. It might he hardware, it might be trap handling > it might be a buggy chip or a general flaw in a stepping > > I wouldnt rule out hardware. The 386 can be crashed with an instruction > from userspace > > Alan >
This seems to be the conclusion I would infer too. This is the output of cat /proc/cpuinfo: processor : 0 cpu : 486 model : DX/4-WB vendor_id : AuthenticAMD stepping : 4 fdiv_bug : no hlt_bug : no fpu : yes fpu_exception : yes cpuid : yes wp : yes flags : fpu bogomips : 49.86
I tried the same program (containing INVD instruction) on a 486 from Intel, nothing spectular happened. Though I did not get fault there too, at least no crash. As far as my knowledge goes INVD should be a privileged instruction on both 486 and Pentium. AMD can produce such CPUs where a userspace program having invd instruction can crash the machine. The poor OS can't help if Hardware is buggy.
Cheers, Praveen
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---------------------------------------------------------------------- Praveen Dwivedi pkd@sequent.com --
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