how to create early build deps?

[Kees Cook <kees@kernel.org>]

Hi!

I am stumped...

I swear there was a time when changing the gcc-plugins would trigger a
full rebuild of all kernel sources. I tried to bisect where that stopped
happening, but it went back far enough that things stopped building with
my compiler at all. ;)

Anyway, I need this also for the Clang randstruct seed file -- if it
changes, we need to rebuild everything. I thought this worked back in
v5.19 when I moved the randstruct seed generation into scripts/basic[1],
but regenerating it doesn't trigger a rebuild (with v5.19 nor current
Linus nor linux-next):

$ make O=clang-all LLVM=1 allmodconfig kernel/seccomp.o
make[1]: Entering directory '/srv/code/clang-all'
...
  GENSEED scripts/basic/randstruct.seed
...
  CC      kernel/seccomp.o
make[1]: Leaving directory '/srv/code/clang-all'

$ rm clang-all/scripts/basic/randstruct.seed

$ make O=clang-all LLVM=1 kernel/seccomp.o
make[1]: Entering directory '/srv/code/clang-all'
  GEN     Makefile
  GENSEED scripts/basic/randstruct.seed
  DESCEND objtool
  CALL    ../scripts/checksyscalls.sh
  INSTALL libsubcmd_headers
make[1]: Leaving directory '/srv/code/clang-all'

kernel/seccomp.o doesn't get rebuilt :(

By what mechanism can I convince kbuild to rebuild everything if
randstruct.seed (or the gcc-plugins) are changed?

Thanks!

-Kees

[1] be2b34fa9be3 ("randstruct: Move seed generation into scripts/basic/")

-- 
Kees Cook