https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55930
--- Comment #9 from Richard Purdie <richard.purdie at linuxfoundation dot org> --- (In reply to Jonathan Wakely from comment #8) > (In reply to Richard Purdie from comment #6) > > Its part of a Yocto Project build and we would only ever build it once so we > > don't need/want the overhead of the dependency tracking information. > > But is there any noticeable overhead when using GCC to bootstrap? > > Automake documents the option as: > > Some compilers do not offer any practical way to derive the list of > dependencies as a side-effect of the compilation, requiring a separate > run (maybe of another tool) to compute these dependencies. The performance > penalty implied by these methods is important enough to disable them by > default. > > That doesn't apply here though, because GCC is generating the dependencies > via -MD as a side effect of compilation. So there should be no need to use > the option (other than saving a bit of disk space during the build). We pass this option in globally to anything using automake so whilst for one piece of software it might not be a huge gain, over a complete Linux stack built from source the disk space (lack of IO) speed wins are useful alone.
