Hi Linus.
> But the reason for this email to you is simply to ask whether you
> use/have any tools for seeing these kinds of deep include chains.
Not exactly what you ask for - but we have make V=2
Example:
$ touch include/uapi/linux/elf-em.h
$ make V=2
CALL scripts/checksyscalls.sh - due to target missing
DESCEND objtool
CC init/main.o - due to: include/uapi/linux/elf-em.h
CHK include/generated/compile.h
CC init/version.o - due to: include/uapi/linux/elf-em.h
CC init/do_mounts.o - due to: include/uapi/linux/elf-em.h
CC init/do_mounts_initrd.o - due to: include/uapi/linux/elf-em.h
CC init/do_mounts_md.o - due to: include/uapi/linux/elf-em.h
...
With V=2 kbuild will try to tell you why a target is rebuild.
This can sometimes be useful.
Here kbuild will tell you: - due to: include/uapi/linux/elf-em.h
Which may be a good clue.
But you need to figure out yourself why a certain file
depends on include/uapi/linux/elf-em.h
One way is to look at the .cmd file for a target:
$ cat init/.do_mounts_md.o.cmd
...
include/linux/module.h \
$(wildcard include/config/modules/tree/lookup.h) \
$(wildcard include/config/module/sig.h) \
$(wildcard include/config/module/unload.h) \
$(wildcard include/config/constructors.h) \
$(wildcard include/config/function/error/injection.h) \
include/linux/kmod.h \
include/linux/umh.h \
include/linux/elf.h \
arch/x86/include/asm/elf.h \
arch/x86/include/asm/user.h \
arch/x86/include/asm/user_64.h \
arch/x86/include/asm/fsgsbase.h \
arch/x86/include/asm/msr-index.h \
arch/x86/include/asm/vdso.h \
$(wildcard include/config/x86/x32.h) \
include/uapi/linux/elf.h \
include/uapi/linux/elf-em.h \
...
In the above all the $(wildcard ...) is the CONFIG_ symbols
in the files that trigger a possible dependency on a file
representing the CONFIG_ symbol.
We can see that the target depends on elf-em.h and if we follow
it back we end up with module.h included from do_mounts_md.c
Sam
