[parisc-linux] HPUX binary compatibility

[Matthew Wilcox <Matthew.Wilcox@genedata.com>]

How far do we want to or are we able to go with making constants identical
between HPUX and Linux?

Some syscalls are going to have to be different between the two OSes --
ioctl is the obvious example -- but it would be nice to have to do as
little work as possible.

I've just been through errno.h making the Linux error numbers the same as
the HPUX ones.  This seems pretty sane; I can't imagine that it will have
any negative effect on anything.  Where it gets a little more thorny is
in signal.h -- HPUX uses more than 32 signals.  Is it going to negatively
impact Linux at all to use more than 32?  I see there is space reserved
for them, but I'd like someone to reassure me.

The real thing which bothers me about this is that doing this means that
HPUX and Linux are then allocating from the same numberspace, so where
Linux has things which HPUX doesn't, HPUX might later allocate the same
number for a different extension.

(Of course, if HP want to add Linux binary compatibility to HPUX, now
would be a great time to mention it :-)

-- 
Matthew Wilcox <willy@bofh.ai>
"Windows and MacOS are products, contrived by engineers in the service of
specific companies. Unix, by contrast, is not so much a product as it is a
painstakingly compiled oral history of the hacker subculture." - N Stephenson