Re: RFC: ENOSYS vs SIGSYS for FreeBSD ABIs

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John Baldwin writes:

> From what I can tell though, while POSIX documents both ENOSYS and SIGSYS,
> it does not document the semantics of these (and the one reference I could
> find to SIGSYS specifically noted that the semantics aren't documented since
> there aren't any consistent semantics across systems).

The explanation I heard many years ago, is that SIGSYS was supposed
to make it possible to emulate system-calls in userland, with some
hand-wavy mumbling about pre-shlib binaries not having to know if
you had bought a STREAMS based or socket(2) based network-add-on
product.

To me that sounded like precisely the kind of thing the commercial
UNIX vendors agree on in the late 1980ies, so it satisfied my curiosity.

Any of Sam, Kirk, Eric or TUHS would be a more credible source.

> On the other side, I have _never_ had SIGSYS be an aid.  It's only gotten
> in the way.

+1

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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FreeBSD committer       | BSD since 4.3-tahoe    
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