setting of initial bottom of stack variable in pthread.c (again)

[Jay]

I posted this on the alpha mailing list, but this
might be a better place for it.  From what I
understand, when __pthread_initial_thread_bos is set
in pthread.c, it must be set to cover both the initial
thread and manager thread.  Looking at the
STACK_GROWS_DOWN case, it looks like this variable is
set to STACK_SIZE beyond the space it needs to to
cover the initial and manager thread.  Graphically:
-------------------   top of initial stack
| Initial thread  |
|                 |
-------------------
| Manager thread  |
|                 |
-------------------
| Free space      |
|                 |
-------------------   __pthread_initial_thread_bos

When the very first worker thread gets assigned its
stack space it is getting assigned the space in free
space which is above __pthread_initial_thread_bos
(instead of something below
__pthread_initial_thread_bos as it should since it is
not part of the initial thread), so when thread_self
is called from the first worker thread, thread_self
returns the initial thread, not the worker thread. 
All other threads created after the first worker
thread are assigned memory below
__pthread_initial_thread_bos.  The line that sets
__pthread_initial_thread_bos is
  __pthread_initial_thread_bos =
    (char *)(((long)CURRENT_STACK_FRAME - 2 *
STACK_SIZE) & ~(STACK_SIZE - 1));

Changing the 2 in the above equation to a 1 would
solve the problem of __pthread_initial_thread_bos
being set beyond the free space depicted above.  Is
what is depicted above correct and it's a problem with
the memory the kernel is handing out, or is this a
bug, and the 2 should be a 1 since the stack is
growing down?

Thanks

Jay

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