Re: Questions about the build process

["Gao, Liming" <liming.gao@intel.com>]

Michael:
  There is one bugzilia https://bugzilla.tianocore.org/show_bug.cgi?id=972 on top level makefile generation. Its purpose is to let the make utility figure out how to multi-thread the build and see whether there is the build performance improvement.
  
  Edk2 BaseTools generates AutoGen and Makefile for every module, then build module one by one. Every module has its own compiler flag, its included path, its AutoGen.h and AutoGen.c. So, the module level makefile is generated. 

  I don't use ninja before. Edk2 build has supported multiple thread build to trig Make in parallel. Does ninja improve build performance? 

Thanks
Liming
>-----Original Message-----
>From: Michael Zimmermann [mailto:sigmaepsilon92@gmail.com]
>Sent: Saturday, June 30, 2018 2:47 PM
>To: edk2-devel-01 <edk2-devel@lists.01.org>; Zhu, Yonghong
><yonghong.zhu@intel.com>; Gao, Liming <liming.gao@intel.com>
>Subject: [edk2] Questions about the build process
>
>Out of curiosity I took a closer look at how the build system works
>internall(especially the Makefile generation and parallel builds) and
>I got some questions which I hope you can answer:
>
>Why are we using make at all?
>As far as I can see we're not using any special make functionality and
>most dependency calculation is done in the python build tool anyway.
>So why don't we just run the build commands ourselves from within the
>build tool?
>
>Why is every module being build separately / Why don't we generate one
>makefile which does everything ?
>To give an opposite view on the previous question, why don't we
>generate makefiles which contain the whole internal dependency graph
>so the build tool can then call a top level 'make' and not worry about
>anything. We wouldn't even have to implement any kind of parallel
>build support(which we currently have a lot of code for) because make
>would do that for us.
>
>If scrambled log output during parallel builds is a concern, then we
>could switch to the "ninja" build system which would probably be way
>more suited for edk2's usecase because it's a pretty fast low level
>language which also gives you proper logs when building in parallel.
>ninja is available for linux, mac and windows.
>
>Thanks
>Michael