errno/h_errno

[Florian Weimer]

* Wilco Dijkstra:

>> I agree, and for the unlikely case where dlmopen is used we have
>> glibc.rtld.optional_static_tls to overcome possible issues.
>
> Couldn't that be automatic for large TLS in dlmopen? Also why don't we
> have a glibc.rtld.static_tls=N tunable for static TLS reservation? Then only
> applications which use dl(m)open with large TLS sizes would need to pay
> the price of reserving extra memory per thread, but they will still benefit
> from the low overhead of static TLS.

There is a potential future where dlmopen is not on obscure interface,
but a basic compositional tool used to avoid accidental symbol
interposition.  But these separate namespaces may not actually need
separate libcs (and can share errno, malloc etc.), so perhaps
initial-exec references to errno are not an obstacle to that.

But the DF_STATIC_TLS flag issue remains.

Thanks,
Florian