In article <1992Oct19.153951.6649@lucrece.robots.ox.ac.uk> jon@robots.ox.ac.uk (Jon Tombs) writes:
quoted text
>
>I think bsd gives a SIGBUS if a user program does a inb() or outb() call,
>this would seem to be more appropriate than SIGSEGV under linux.

Actually, this isn't a good idea: linux would have to check why the
protection error happened, and I don't think that is necessary or even
something we want it to do.  The current kernel setup just sees an error
it cannot handle, so it sends a SIGSEGV.  No special cases, no chacks
why it happened etc. 

One good (or at least better) argument for SIGBUS being included (and
one I have been thinking about) is that a 486 actually has an alignment
trap, which under sysv-386 does seem to result in a SIGBUS (not that I
have tried: just read about it somewhere).  I haven't bothered about it,
as I think the alignment trap is disabled under linux anyway.  Besides,
I don't see any reason for an alignment fault unless the processor
really isn't able to handle unaligned transfers - but a 486 is perfectly
capable of doing them, even if they are a bit slower.  And gcc generally
doesn't generate such code anyway. 

                Linus