[PATCH] kbuild: unexport sub_make_done to fix child make invocations

[Conor Dooley]

On Wed, Mar 04, 2026 at 09:01:45AM -0600, Tom Rini wrote:
> On Wed, Mar 04, 2026 at 09:54:22AM +0000, Conor Dooley wrote:
> > On Tue, Mar 03, 2026 at 12:50:55PM -0600, Tom Rini wrote:
> > > On Fri, 13 Feb 2026 19:47:34 -0700, Simon Glass wrote:
> > > 
> > > > The exported sub_make_done variable leaks into the environment of all
> > > > child processes. When make targets like tcheck spawn independent make
> > > > invocations with O=, those child makes inherit sub_make_done=1, skip
> > > > the KBUILD_OUTPUT setup and try to build in the source tree.
> > > > 
> > > > There is a workaround that resets sub_make_done to 0 for specific test
> > > > targets, but this isn't great since it has tolist every target that
> > > > spawns independent make invocations.
> > > > 
> > > > [...]
> > > 
> > > Applied to u-boot/master, thanks!
> > > 
> > > [1/1] kbuild: unexport sub_make_done to fix child make invocations
> > >       commit: 4284306d22c5b6d64ecd62b462551d9d313c8104
> > 
> > 
> > This breaks the build for me:
> > make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- O=build microchip_mpfs_generic_defconfig
> >   GEN     Makefile
> > #
> > # configuration written to .config
> > #
> > make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- O=build
> >   HOSTCC  scripts/basic/fixdep
> >   GEN     Makefile
> >   HOSTCC  scripts/kconfig/conf.o
> >   YACC    scripts/kconfig/zconf.tab.[ch]
> >   LEX     scripts/kconfig/zconf.lex.c
> >   HOSTCC  scripts/kconfig/zconf.tab.o
> >   HOSTLD  scripts/kconfig/conf
> > scripts/kconfig/conf  --syncconfig Kconfig
> > ***
> > *** Configuration file ".config" not found!
> > ***
> > *** Please run some configurator (e.g. "make oldconfig" or
> > *** "make menuconfig" or "make xconfig").
> > ***
> > make[4]: *** [/stuff/u-boot/scripts/kconfig/Makefile:75: syncconfig] Error 1
> > make[3]: *** [/stuff/u-boot/Makefile:702: syncconfig] Error 2
> > make[2]: *** [../Makefile:189: __sub-make] Error 2
> > make[1]: *** No rule to make target 'include/config/auto.conf', needed by 'include/config/uboot.release'.  Stop.
> > make: *** [Makefile:189: __sub-make] Error 2
> 
> That's odd. What host distro and make? I don't see that on Ubuntu 24.04.

Originally my CI found it in a docker container with "from: ubuntu:noble",
so 24.04. I reproduced it locally on debian unstable with make 4.4.1
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