I like my build output without unnecessary noise. A perfect build system would for me just have some kind of progress indicator, and then in the end write "Success" if the build succeeded :)
It gets a little harder when the build fails, as some information about where the failure was and what went wrong is really helpful :)
Today I discovered one way of getting a little closer to this, for me, ideal world. It is possible from the mozconfig file to tell the build system not to produce the "Entering directory" and "Leaving directory" messages that in my eyes just clutter the build output in 99% of the cases.
The way to do it is to add a --no-print-directory option to the MOZ_MAKE_FLAGS, like:
If you want to add multiple options it can be done like this:
mk_add_options MOZ_MAKE_FLAGS="-j4 --no-print-directory"
The -j4 option tells the build system to have 4 processes running in parallel - be warned thou - I have 1 (one) time seen a build fail due to unlucky timing and using parallel builds (with -j2), it was easily fixed thou, as I just had to build again, giving a slightly different timing and a successful build.