Minimum GCC version for building glibc

[Richard Henderson]

On 11/05/2014 05:34 PM, Joseph Myers wrote:
>> > really looked at what to do when GCC's libatomic would implement certain
>> > atomics (e.g., when the kernel is used) -- should we just use libatomic,
>> > or would we need to keep rolling our own.
> My inclination is to keep rolling our own.  I suspect libatomic might be 
> troublesome in bootstrap builds (where the desire is for glibc built with 
> an initial static-only GCC, itself built without C library headers, to be 
> identical to glibc built from a longer iteration of alternating GCC and 
> glibc builds).  And any libatomic operations based on locks (e.g. the 
> operations for arbitrary-sized types) obviously aren't suitable for glibc 
> use (depending as they do on pthread_mutex_lock).

Agreed, more or less.

I'd been thinking that while we wouldn't actually link against gcc's libatomic
we could, as needed, implement the same __atomic_* functions, so that the
normal builtins Just Work.  We would of course not export these symbols, so
that normal user use of these would bind to libatomic.


r~