Re: [patch 11/11] x66/vdso: Add CLOCK_TAI support

[Thomas Gleixner]

On Fri, 14 Sep 2018, Andy Lutomirski wrote:
> > On Sep 14, 2018, at 5:50 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > 
> > With the storage array in place it's now trivial to support CLOCK_TAI in
> > the vdso. Instead of extending the array to accomodate CLOCK_TAI, make use
> > of the fact that:
> > 
> > - CLOCK ids are set in stone
> > - CLOCK_THREAD_CPUTIME is never going to be supported in the VDSO so
> >   the array slot 3 is unused
> > - CLOCK_TAI is id 11 which results in 3 when masked with 0x3
> > 
> > Add the mask to the basetime array lookup and set up the CLOCK_TAI base
> > time in update_vsyscall().
> 
> Thatâs... horrible. In an amazing way. Can you add BUILD_BUG_ON somewhere
> to assert that this actually works?

Sure, but changing any of the clock ids will cause more wreckage than that.

Thanks,

	tglx