libpthread version bump

Peter Wemm peter at wemm.org
Fri Apr 22 14:29:22 PDT 2005


On Friday 22 April 2005 02:03 pm, Daniel Eischen wrote:
> On Fri, 22 Apr 2005, Peter Wemm wrote:
> > The only other idea that springs to mind is to use dlsym() to test
> > for the symbol, but that has its own serious problems.  If the
> > pragma weak stuff works, then I'd be happy with that.
> >
> > The only gotcha is that we still have to test for the possibility
> > that the *base syscalls return EINVAL..  This will happen for
> > booting old kernel.old files, and I'm not sure that current is
> > quite robust enough yet that people aren't going to want to be able
> > to rewind a few months.
> >
> > So, the options are:
> > 1) test for have_gsbase using weak (or dlsym).
> > 2) As previously suggested, add implemenations to libc.so.5 and
> > pick them up via a fresh compat5x.  We can add an implementation to
> > libc.so.5.  Since they wouldn't be used on 5.x, there is no risk of
> > breaking anything.  The functions would only do something when
> > running the libc.so.5 library with a 5.x application on 6.x.
> >
> > I have a slight preference for #2, but that would mean adding two
> > tiny (but otherwise unused) libc.so functions very late in the
> > cycle.  If re@ would allow it, I'd like that.  But the #pragma weak
> > option also works for me.
> >
> > #2 can also make it a little easier to run 5.x i386 binaries on
> > amd64 - we could kill of most of those nasty ifdefs.
> >
> > #1 would end up something like:
> >   #pragma weak i386_set_gsbase
> >   #pragma weak i386_get_gsbase
> >   static void (*have_get_gsbase)(void) = i386_get_gsbase;
> >   static void (*have_set_gsbase)(void *) = i386_set_gsbase;
> >   if (have_i386_get_gsbase == NULL || have_get_gsbase() == -1) {
> >     use_ldt();
> >   } else {
> >     use_gsbase();
> >   }
> > I think that is sufficient to test if the symbols are present and
> > test if they work at runtime...
>
> I worked up a quick patch.  It compiles, but it will be some time
> before I can try it.
>
>   http://people.freebsd.org/~deischen/kse/libpthread.diffs

I think this will work.  If somebody would like to try this, I think it 
would be a good thing.  (rebuild libpthread.so.0, and run a 5.x 
threaded binary that would normally have the undefined symbols)

-- 
Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5


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