tools/unix.mk: Pass APPDIR to arch's Makefile

[xiaoxiang781216]

Summary

make link custom library from apps/staging working, continue the work #8253

Impact

No by default

Testing

Internal build server

[acassis]

@xiaoxiang781216 will it slow down the building process? Every time I ran "$ ./tools/refresh.sh --silent --defaults all" it spend dozen of minutes to finish. We need some way to speed it up or make it run in parallel, any idea how to find out the bottleneck?

[xiaoxiang781216]

@xiaoxiang781216 will it slow down the building process?

No, APPDIR come from environment directly which is very fast.

Every time I ran "$ ./tools/refresh.sh --silent --defaults all" it spend dozen of minutes to finish. We need some way to speed it up or make it run in parallel, any idea how to find out the bottleneck?

From my experience, here is some point need to consider:

1. Makefile invoke too many shell script(e.g. use the correct path) in the hot path(e.g. Remove duplicate calls and optimize compilation speed #7076)
2. Recursive construction lead the same Makefile is parsed many times(https://accu.org/journals/overload/14/71/miller_2004/)
3. The speed of make itself isn't fast than the new build tool like ninja

The better way to improve the speed and maintainence is switching to modem build system(e.g. CMake #6718). I don't believe we have enough resource and talent people to improve the current Makefile base system.