FreeBSD port

[cyring]

Purpose

Based on 7e9a355#r51613397 the followings are about the attempt to port CoreFreq to FreeBSD

Impacts

Compiler

Starting with FreeBSD 10.X clang is installed as cc
Compiling with cc

• As of today, CoreFreq Daemon and Client can be built with clang version 11.1 for Linux

make CC='clang' clean corefreqd corefreq-cli

• Unfortunately the kernel module build fails with those errors:

make[1]: Entering directory '/usr/lib/modules/5.12.8-arch1-1/build'
  CC [M]  src/CoreFreq/corefreqk.o
clang-11: error: unknown argument: '-fplugin-arg-structleak_plugin-byref-all'
clang-11: error: unsupported option '-mrecord-mcount' for target 'x86_64-pc-linux-gnu'

[danfe]

User-land utilities currently require some patching, but not too much; apart from avoiding peeking into opaque locale_t type, there are things like different order of the qsort_r(3) arguments, some missing Linux-specific signals, non-POSIX strerror_r(3) in Glibc, etc. I can upload them somewhere if there's interest, they allow those programs to build and work on FreeBSD, however, they are not very useful without the bigger challenge which is the kernel module itself, and I've just started this work.

[cyring]

I also have a few FreeBSD cases from previous project XFreq

• I/O calls
• Basic pthreads