Shared page and related goodies for ARMv7

[Andrew Turner]

On Tue, 29 Sep 2015 19:23:12 +0300
Konstantin Belousov <kostikbel at gmail.com> wrote:

> On Tue, Sep 29, 2015 at 09:19:42AM -0600, Ian Lepore wrote:
> > I just skimmed through the patch quickly and the main thing that
> > jumps out at me is that what you've done works only on rpi2 and
> > aarch64, because those are the only platforms that support that
> > timer hardware. (That means I can't test it, but once I get your
> > patch in a usable form I can have a shot at implementations for
> > other timers).
> Cortex A7/A15 and whole ARMv8 is not too bad set of machines for fast
> gettimeofday() IMO, at least for the first try.  I am willing to
> adjust both approach and code it for wider usefulness.

It's an optional feature on ARMv7, we only build it for Exynos 5,
Raspberry Pi 2, and QEMU virt.

How will it work on hardware that lacks the generic timer? Will it
always try and use this hardware, even if it's missing, or do we need
to tell userland what to use, with a fallback to a syscall? 

Andrew