Re: Dependency issue through subdir's

From: Michal Marek
Date: Mon Jan 25 2016 - 08:22:25 EST

On 2016-01-25 12:33, Kieran Bingham wrote:
> This is functional on a make -j1 build, however at -j2 and above (from a
> clean build), kbuild attempts to generate my file before
> include/generated/timeconst.h resulting in the following error:
> --- 8< ---
> GEN scripts/gdb/linux/
> In file included from sources/linux/include/linux/ktime.h:25:0,
> from /linux/include/linux/rcupdate.h:47,
> from /linux/include/linux/rbtree.h:34,
> from /linux/include/linux/mm_types.h:9,
> from /linux/arch/x86/include/asm/pgtable.h:448,
> from /linux/scripts/gdb/linux/
> sources/linux/include/linux/jiffies.h:10:33: fatal error:
> generated/timeconst.h: No such file or directory
> --- >8 ---
> 2) Move the code that generates this file to /Kbuild. However I don't
> like the idea of putting non-essential generator at the top level build

You can keep the code in scripts/gdb/..., just move it out of $(always)
and have the toplevel Kbuild file call something like

$(MAKE) $(obj)=scripts/gdb/linux build_constants

> 3) Add #ifndef __GENERATE_CONSTANTS_PY__ across any reference to
> generated header files, such as in ktime.h, and define that with my
> Preprocessor statement.

If you do not need the generated headers, this might be the least evil.
We already have the COMPILE_OFFSETS and __GENERATING_BOUNDS_H defines
for a similar purpose.