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nacl and CPU frequency.



I'm trying to get nacl built on more architectures in debian, in particular I want to see it build on arm*.

In order to build successfully nacl needs to determine the CPU frequency (the CPU frequency determined at build time is not used in the final binaries afaict but if it's not determined then the build will fail as it will consider the implementation broken and if it can't find any non-broken implementations it won't build).

Currently the generic implementations (there are also some CPU specific implementations) do this by looking at various locations in /proc and /sys, specifically (in order)

/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
/sys/devices/system/cpu/cpu0/clock_tick
/proc/cpuinfo

If it fails to find the info in /sys or /proc it then falls back to trying lsattr and psrinfo but neither of theese seem to exist in current debian.

Unfortunately it seems /sys/devices/cpu/cpu0 doesn't exist on all systems (even if /sys is mounted) and while /proc/cpuinfo always seems to exist it doesn't always have CPU frequency information.

Now for my questions (the first is directed at developers in general, the second is directed at Sergiusz but if others know the answer I wouldn't mind them asking it)

Is there a portable way of determining CPU frequency in debian?
Do you known how important it is to have an accurate CPU frequency determination for nacl. e.g. if true CPU frequency can't be determined would it be ok to use bogomips instead?


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