Messages in this thread | | | Subject | Re: [RFC PATCH] powerpc/32: Switch VDSO to C implementation. | From | Christophe Leroy <> | Date | Fri, 20 Dec 2019 19:24:22 +0100 |
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Hi Thomas,
In do_hres(), I see:
cycles = __arch_get_hw_counter(vd->clock_mode); ns = vdso_ts->nsec; last = vd->cycle_last; if (unlikely((s64)cycles < 0)) return -1;
__arch_get_hw_counter() returns a u64 values. On the PPC, this is read from the timebase which is a 64 bits counter.
Why returning -1 if (s64)cycles < 0 ? Does it means we have to mask out the most significant bit when reading the HW counter ?
Christophe
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