RE: [linuxsh-dev] Different old_mmap behavior in 2.4.5 and 2.4.8

[Bao C. H. <ba...@se...>]

I am sending this message also to Ulrich Drepper, since
the ChangeLog indicated that he removed the MAP_FIXED in
the following.  It is causing problems running pthread
applications in the sh4-linux environment.

Following is the relevant segment of linuxthreads that is
broken:

In function pthread_allocate_stack(), file manager.c:
.......
#  ifdef _STACK_GROWS_DOWN
      new_thread = default_new_thread;
      new_thread_bottom = (char *) (new_thread + 1) - stacksize;
      map_addr = new_thread_bottom - guardsize;
      res_addr = mmap(map_addr, stacksize + guardsize,
                      PROT_READ | PROT_WRITE | PROT_EXEC,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
      if (res_addr != map_addr)
        {
          /* Bad luck, this segment is already mapped. */
          if (res_addr != MAP_FAILED)
            munmap (res_addr, stacksize + guardsize);
          return -1;
        }
.......

We resort to patching the MAP_FIXED back to linuxthreads
until we get a resolution on this problem.

Thanks.
Bao

> -----Original Message-----
> From: lin...@li...
> [mailto:lin...@li...]On Behalf Of Bao C. Ha
> Sent: Tuesday, September 11, 2001 9:55 AM
> To: 'David Woodhouse'
> Cc: lin...@li...; lin...@m1...
> Subject: RE: [linuxsh-dev] Different old_mmap behavior in 2.4.5 and
> 2.4.8 
> 
> 
> 
> > 
> > >  Is this supposed to be the correct area?  What changes 
> > make the newer
> > > kernels to return different pointers? 
> > 
> > Looking at the numbers, I'd be inclined to guess that it's 
> > moved due to
> > cache aliasing. And hence that it's not very likely to get 'fixed'. 
> > 
> Either the sh4 kernel has to be fixed, or linuxthread has to be fixed.
> MAP_FIXED was removed from linuxthreads sometimes earlier this year.
> Any serious applications using linuxthreads will exhibit the same
> problem.
> 
> Bao
> 
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