[uClibc]syscalls.c

[Steve Thayer]

I think a reasonable compromise can be reached here. As Michael
states below, Linuxthreads does override some of the syscalls
to set the cancellation type, but only about 20 of the 120+
syscalls implemented by uClibc.  So we'd be looking at only 
20 additional weak aliases.  If you'd like, I can have those
optionally compiled in only if pthread support is compiled in to
uClibc (this might make the code a little uglier, but it would
save space in the binary).

I also won't need to introduce any of the __function() calls to
uClibc if I change Linuxthreads to use uClibc's naming convention
instead (i.e. call function() instead of __function()).  The end
result would be the same, and I wouldn't have to add any new weak
aliases.

Linuxthreads also uses some of the sched_* syscalls, which are not
currently implemented in uClibc, so I would have to add those as
well.  There's only about five needed, so they shouldn't take up
much space, and again I can optionally compile them in when
including pthread support.

-Steve



> -----Original Message-----
> From: Michael Shmulevich [mailto:michaels at jungo.com]
> Sent: Sunday, June 24, 2001 1:20 AM
> To: andersen at lineo.com
> Cc: Steve Thayer; Uclibc (E-mail)
> Subject: Re: [uClibc]syscalls.c
> 
> 
> > 
> >>Also, most of the syscalls that are implemented use strong names
> >>instead of weak, so it isn't possible to link in a different
> >>implementation if necessary.  Glibc, for example, defines the
> >>syscall as "__name" and does a weak_alias(__name, name).  That way
> >>you can write your own "name" implementation which overrides the
> >>syscall.  uClibc defines the syscall as "name", which prevents
> >>overrides.  Again, is there a reason for this that I just don't see?
> >>
> > 
> > Each weak symbol takes a bit of space in the final binary.  
> And also since I
> > think glibc is being somewhat abusive with the number of 
> weak symbols it uses,
> > and since uClibc is intended to be small.
> > 
> > Do you find you have a need to override syscalls?
> 
> Linuxthreads library have an urge to override almost all syscalls, 
> setting its cancelation type to something. It expects to find some 
> syscalls to be named in a style of __libc_syscall() and not just 
> syscall(). Except that, it also expects to use some libc 
> functions using 
> their internal name, like __function()... Expect to introduce some 
> number of those to uClibc too.
> 
> 
> -- 
> Sincerely yours,
> Michael Shmulevich
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