What can a thread do with PTHREAD_STACK_MIN?

[Florian Weimer]

On 12/21/2017 06:09 PM, Carlos O'Donell wrote:
> Therefore I would propose an addendum about cancellation:
> ~~~
> The implementation only guarantees that a thread with PTHREAD_STACK_MIN
> can be created, but such space does not take into consideration the
> thread's stack requirements to execute the start routine. No additional
> space, beyond that for the start routine, should be required to join the
> thread again.
> 
> Therefore for a thread to be both startable and joinable it must have
> PTHREAD_STACK_MIN stack and the stack required for start routine as a
> minimum.
> 
> The value of PTHREAD_STACK_MIN does not include enough stack for the
> thread in question to be cancelled. Cancellation requires an additional
> unspecified amount of stack that depends on the cancellation handlers
> to run and when the cancellation is acted upon.
> ~~~

I think this should mention signal handlers (including signals which are 
send to the process and may randomly end up on this thread), lazy 
binding, and, at least for now, static TLS.

I'm also not sure where we would put this information, due to the 
general lack of pthread documentation.

Thanks,
Florian