== Basic build ==

1. Edit config.mk. Follow the comments there.
   Optionally you can change compiler settings in include_[GCC|CLANG|ICC|MIC].mk.
   Please note that only the default compiler flags GCC are supported and tested.
2. make (Builds hwloc, lua, Likwid libraries, access daemons and likwid-bench)
3. make install (this is required for likwid-pin and if you use the accessDaemon)

Only the default flags set are tested. As it is not possible to test all
compiler setting variants the Intel icc compiler and Clang is only build tested.
A basic function test is done for the icc binary. The only variant fully tested
is gcc with default compiler flags. It is therefore recommended to use gcc with
the default flags. If you want to use and build the Fortran interface you can mix
GCC with the Intel Fortran Compiler (default setup). You can change the Fortran
compiler in make/include_[GCC|CLANG|ICC|MIC].mk.

*NOTICE*

All generated files are located in the [GCC|ICC|CLANG|MIC] build directory.
This includes the dependency files, object files. The
generated source files and the pas and assembly files for likwid-bench are build
in bench/[GCC|ICC|CLANG|MIC].
If you debug your likwid-bench benchmarks you can look at all
intermediate build files and also the final assembly code.

== Build on Xeon Phi ==
For builds for the Xeon Phi coprocessor, the accessDaemon and the frequency
daemon are disabled. Moreover, the access mode is set to 'direct'. This was made
because it is important to run as few processes as possible on the Xeon Phi and
the accessDaemon would start one process per hardware thread.
In order to build Likwid for the Xeon Phi processor, you have to change the
RPATHS variable in make/include_MIC.mk to point to the folder with the Intel
libraries like libimf.so. This is crucial because when using an suid-root
executable, the LD_LIBRARY_PATH gets lost but Likwid still needs to know where
the Intel libraries reside.
After installation change the owner of likwid-lua to root and set the suid-root
bit for likwid-lua:
chown root <BINPATH>/likwid-lua
chmod u+s <BINPATH>/likwid-lua
Afterwards Likwid can be used as anywhere else.

== Known problems ==

On very old systems with old kernels (< 2.6.7) or old glibc versions likwid
is build with reduced funtionality. This includes missing support for NUMA
and pinning.
likwid-setFrequencies can only be used if the acpi_cpufreq module is loaded. It
is not possible to fix the frequency with the intel_pstate module.

== Additional Targets ==

make clean     -  clean the object directory
make distclean -  clean also the executables/libraries
make uninstall -  delete installed files
make docs      -  generate html documentation using doxygen
make local     -  set paths in Lua files to work from current directory
                  (for testing only! Uses already installed access daemons and
                  libraries. Often you have to set the LD_LIBRARY_PATH to the
                  contain the current folder)

== Dependencies ==
Most parts of the Likwid suite do not have external dependencies that need to be
installed before you can build Likwid. If external libraries are used, they are
shipped with Likwid.

Included dependencies:
- hwloc
- Lua
- Perl Template toolkit

Build dependencies:
- C compiler (commonly gcc, but clang and icc are also possible)
- make
- Perl

Runtime dependencies for likwid-perfscope:
- gnuplot

Runtime dependencies for likwid-agent (if enabled in configfile):
- gmetric (Output to Ganglia Monitoring System)
- rrdtool (Output to RRDs)
- logger (Output to syslog)

For the HTML documentation you further need doxygen.

== Build  accessDaemon ==

Change path for the accessDaemon:

1. Edit config.mk and configure path in ACCESSDAEMON variable. You can overwrite
   it later in likwid.cfg
2. Set the desired default ACCESSMODE. You can overwrite this on the command
   line or likwid.cfg.
2. make will also build the accessDaemon
3. Install with (sudo) make install

With the standard make install target the daemon will also be installed in
to the path in $ACCESSDAEMON. It also sets the user to root and the suid bit.

== Setup of msr module ==

likwid-perfctr, likwid-powermeter, likwid-agent, require the Linux msr kernel
module. This module is part of most standard distro kernels. You have to be root
to do the initial setup.

1. Check if the msr module is loaded with 'lsmod | grep msr'.
   There should be an output.
2. If the module is not loaded, load it with 'modprobe msr'. For automatic
   loading at startup consult your distros documentation how to do so, commonly
   by adding 'msr' to /etc/modules.
3. Adopt access rights on the msr device files for normal user. To allow
   everybody access you can use 'chmod o+rw /dev/cpu/*/msr'.
   This is only recommended on save single user desktop systems and might be not
   enough to grant access to anybody because of POSIX capabilites or other
   security features of your distro.

As a general access to the msr registers is not desired on security sensitive
systems, you can either implement a more sophisticated access rights settings
with e.g. setgid. A common solution used on many other device files, e.g. for
audio, is to introduce a group and make a chown on the msr device files to that
group or use dbus rules. Now if you execute likwid-perfctr with setgid on that
group the executing user can use the tool but cannot directly write or read the
msr device files.

A secure solution is to use the accessDaemon, which encapsulates the access to
the msr device files and performs an address check for allowed registers. For
more information how to setup look at the HTML documentation.

A demo for a root exploit involving the msr device files was published. As
a consequence the security settings for access to the msr device files are
tightened in recent kernels. The exploit used a specify register to alter the
entry point for the current process to a malware. The daemon grants access only
to hardware performance counter related registers.

Just setting the file access rights or using suid root on the access daemon is
not sufficient anymore for some distros. You have to register your binary at the
libcap now to get access. This is only necessary if above setup does not work.

You register the necessary capability by calling

sudo setcap cap_sys_rawio+ep EXECUTABLE

on the executables. This is only possible on local file systems.
The only feasable way is to register the likwid-accessD and proxy all access over it.

If you have still problems please let me know on the likwid mailing list:
http://groups.google.com/group/likwid-users





