[PATCH 2/5] libstdc++ futex: Use FUTEX_CLOCK_REALTIME for wait

[Joseph Myers]

On Fri, 12 Jan 2018, Torvald Riegel wrote:

> Another option might be to require a minimum glibc version on Linux, and
> build libstdc++ for that.  That would yield a minimum kernel version as
> well, and we may can make use of other things in return such as syscall
> wrappers.

A minimum glibc version of course only applies when libstdc++ is being 
built with glibc - it can also be built with other C libraries using the 
Linux kernel (and some - at least uClibc - define __GLIBC__ to pretend to 
be some old glibc version).

One thing to note regarding minimum glibc (or kernel) versions is it can 
be useful to use new GCC to build binaries to run on older systems - which 
means building new GCC as a cross compiler with a sysroot with an old 
glibc version in it.  So the relevant question for establishing a minimum 
glibc or kernel version is not what systems people are using to develop 
GCC, but what systems they might want to deploy binaries built with 
current GCC onto.

-- 
Joseph S. Myers
joseph@codesourcery.com