[Issue 14863] CLOCK_BOOTTIME should be optional to support <2.6.39 kernels

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14863

--- Comment #1 from Jonathan M Davis <issues.dlang at jmdavisProg.com> ---
Great... People are still using kernels that old? This sort of problem didn't
even occur to me. We really aren't set up to have different C headers depending
on the kernel version and the like, and we're certainly not set up to support
different ClockTypes depending on your kernel version - though in theory, it's
supposed to be set up so that if you don't explicitly use a particular
ClockType, it wouldn't matter.

The GC and runtime should only care about MonoTime itself - i.e.
MonoTimeImpl!(ClockType.normal) and not any of the other instantiations of
MonoTimeImpl. I guess that in one of the rounds of changes that we made
relating to static constructor bugs must have resulted in the clock frequency
being grabbed for all of the ClockTypes that the system supports (or at least
supposedly supports). *sigh*

The simplest solution of course would be to simply get rid of
ClockType.bootTime, though that definitely would suck, and I don't know how
we'd decide when to readd it (I really don't want to have start worrying about
kernel versions). Other than that, presumably, we have to make sure that none
of the ClockTypes other than ClockType.normal get used in any way unless
someone uses them in their own program.

I guess that I'll have to find time to dig into this ASAP.

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