On Tue, Sep 10, 2013 at 12:38 PM, John Stultz <john.stu...@linaro.org> wrote: > On Tue, Sep 10, 2013 at 4:31 AM, Stephan Mueller <smuel...@chronox.de> wrote: >> Hi, >> >> /dev/random uses the get_cycles() function to obtain entropy in addition to >> jiffies and the event value of hardware events. >> >> Typically the high-resolution timer of get_cycles delivers the majority of >> entropy, because the event value is quite deterministic and jiffies are very >> coarse. >> > [snip] >> The following patch uses the clocksource clock for a time value in case >> get_cycles returns 0. As clocksource may not be available during boot time, >> a flag is introduced which allows random.c to check the availability of >> clocksource.
Also, note that at the end of timekeeping_init(), we may not have been able to access the RTC (as some RTCs require interrupts to access), so on those systems getnstimeofday() may return something close to 0 until the RTC subsystem initializes and sets the current wall time. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
