{make,set,swap}context broken on powerpc32

[Paul Mackerras]

Ulrich Drepper writes:

> Then your code is broken.  It must be possible to use contexts in 
> different threads.  Since this is all explicit scheduling it's easy 
> enough to avoid constructs where the generated code depends on __thread 
> not changing.  For explicit __thread variables it is the programmer's 
> responsibility to avoid them.

Does that last sentence mean that it is the programmer's
responsibility to avoid using __thread variables entirely if he/she is
using setcontext or swapcontext anywhere in his/her program?  Or did
you mean something different?

Paul.