The output "Building configuration X (matching Y)" is not needed when using the build system at the default log level because the build system always writes "Building target 'Z' in configuration 'Y'", so the user already knows the configuration being used.

Due to a separate bug the "Building configuration ..." message is also printed twice, resulting in the output:

[ehelin@ehelin hs-rt]$ make CONF=slow test-hotspot-internal
Building configuration 'x64-slow' (matching CONF=slow)
Building configuration 'x64-slow' (matching CONF=slow)
Building target 'test-hotspot-internal' in configuration 'x64-slow'

which are two lines too much :)

I understand the need for the build systems engineers to have the "Building configuration ..." output for debugging purposes, perhaps it can be moved to LOG_LEVEL debug or something similar?