On 06/10/2015 15:06, Peter Maydell wrote: > Looking closer, clock_gettime() also has a userspace > only fastpath in the VDSO.
Yup, hence the patch that changed the default cpu_get_real_ticks() implementation to get_clock(). >> > Could we just use CNTVCT_EL0? Which cores have it? > > Not guaranteed to be enabled for userspace access by the kernel, > and even if it is enabled, the kernel folks don't (last time I > checked) consider this userspace ABI -- it's only there for > the benefit of the VDSO. Ok, thanks. > (CNTVCT_EL0 is how the fast clock_gettime > and getimeofday paths are implemented.) Yes. Paolo
