build: Add missing dependencies when building kernel for amd64.

[• hselasky]

Summary

The elf-vdso32.so.o and elf-vdso.so.o targets build some header files
needed when building some other targets. Add the missing dependencies
to avoid compilation errors.

MFC after: 1 week
Sponsored by: NVIDIA Networking

[imp]

It would be better if we depended on the header files directly... but if these really are files otherwise not mentioned in the build system and are purely a side effect of the o creation then this is goid.

[• hselasky]

In D40192#915023, @imp wrote:

It would be better if we depended on the header files directly... but if these really are files otherwise not mentioned in the build system and are purely a side effect of the o creation then this is goid.

Yes, I know, but there is no separate target for the header file at the moment. The .sh files in question do a lot of stuff.

So I thought I would just depend on the object file being there, implying all the other files are generated too.

[kib]

Does config(8) allow to specify that a build step produces more than one file? This is the problem causing the use of elf-vdso.so.o as a build indicator.

Perhaps you could add vdso_offset.h as a file to files.amd64, and there specify a dependency on .o together with empty build rule.

[• hselasky]

In D40192#915080, @kib wrote:

Does config(8) allow to specify that a build step produces more than one file? This is the problem causing the use of elf-vdso.so.o as a build indicator.

I will double check config(8), but I suspect it is quite simple in that regards.

Perhaps you could add vdso_offset.h as a file to files.amd64, and there specify a dependency on .o together with empty build rule.

That's possible, but you still need the dependency keyword for the C-files in question. Either you depend on the "elf-vdso.so.o" or you depend on "vdso_offset.h". I don't know which is better.

[kib]

In D40192#915111, @hselasky wrote:

In D40192#915080, @kib wrote:

Perhaps you could add vdso_offset.h as a file to files.amd64, and there specify a dependency on .o together with empty build rule.

That's possible, but you still need the dependency keyword for the C-files in question. Either you depend on the "elf-vdso.so.o" or you depend on "vdso_offset.h". I don't know which is better.

Yes, vdso_offset.h would depend on the vdso. My point is that .c sources depend on vdso_offset.h, which would be a more correct dep edge, than vdso->.c (if possible to express).

[• hselasky]

In D40192#915712, @kib wrote:

In D40192#915111, @hselasky wrote:

In D40192#915080, @kib wrote:

Perhaps you could add vdso_offset.h as a file to files.amd64, and there specify a dependency on .o together with empty build rule.

That's possible, but you still need the dependency keyword for the C-files in question. Either you depend on the "elf-vdso.so.o" or you depend on "vdso_offset.h". I don't know which is better.

Yes, vdso_offset.h would depend on the vdso. My point is that .c sources depend on vdso_offset.h, which would be a more correct dep edge, than vdso->.c (if possible to express).

In both cases you will need to add a manual dependency for those C-files in files.amd64 - right?

It is just the formality. C-files depend on H-files.

So I'll add a new dummy target for the header file, and use that as a dependency.

--HPS