linux-kernel - Re: [PATCH] kbuild: install-extmod-build: Properly fix CC expansion when ccache is used

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Message-ID: <yylihpoko4xxk4i5o7qfuidn4ve4vjedfbgc3uzysgvhla2fyb@2c5inm3xmwky>
Date: Mon, 10 Nov 2025 10:28:30 +0200
From: Abel Vesa <abel.vesa@...aro.org>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Nicolas Schier <nsc@...nel.org>, 
	Masahiro Yamada <masahiroy@...nel.org>, Jeff Johnson <jeff.johnson@....qualcomm.com>, 
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kbuild: install-extmod-build: Properly fix CC expansion
 when ccache is used

On 25-11-09 16:41:24, Nathan Chancellor wrote:
> On Mon, Nov 10, 2025 at 12:26:31AM +0200, Abel Vesa wrote:
> > Currently, when cross-compiling and ccache is used, the expanding of CC
> > turns out to be without any quotes, leading to the following error:
> > 
> > make[4]: *** No rule to make target 'aarch64-linux-gnu-gcc'.  Stop.
> > make[3]: *** [Makefile:2164: run-command] Error 2
> > 
> > And it makes sense, because after expansion it ends up like this:
> > 
> > make run-command KBUILD_RUN_COMMAND=+$(MAKE) \
> > HOSTCC=ccache aarch64-linux-gnu-gcc VPATH= srcroot=. $(build)= ...
> 
> Yup, good old shell quoting... :(
> 
> > So add another set of double quotes, this time escaped, to make sure the
> > aarch64-linux-gnu-gcc isn't expanded to something that looks like an
> > entirely separate target.
> > 
> > Fixes: 140332b6ed72 ("kbuild: fix linux-headers package build when $(CC) cannot link userspace")
> > Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> > ---
> >  scripts/package/install-extmod-build | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build
> > index 054fdf45cc37a8717444b8094daf3e1150a8ccf5..6cce5c41552d520bf069487352fd26417b0b3899 100755
> > --- a/scripts/package/install-extmod-build
> > +++ b/scripts/package/install-extmod-build
> > @@ -63,7 +63,7 @@ if [ "${CC}" != "${HOSTCC}" ]; then
> >  	# Clear VPATH and srcroot because the source files reside in the output
> >  	# directory.
> >  	# shellcheck disable=SC2016 # $(MAKE) and $(build) will be expanded by Make
> > -	"${MAKE}" run-command KBUILD_RUN_COMMAND='+$(MAKE) HOSTCC='"${CC}"' VPATH= srcroot=. $(build)='"$(realpath --relative-to=. "${destdir}")"/scripts
> > +	"${MAKE}" run-command KBUILD_RUN_COMMAND='+$(MAKE) HOSTCC='\""${CC}"\"' VPATH= srcroot=. $(build)='"$(realpath --relative-to=. "${destdir}")"/scripts
> 
> Can we avoid the need for escaping the " by just moving it to the other
> side of the '?
> 
>   "${MAKE}" run-command KBUILD_RUN_COMMAND='+$(MAKE) HOSTCC="'"${CC}"'" VPATH= srcroot=. $(build)='"$(realpath --relative-to=. "${destdir}")"/scripts
> 

Yep, this does the trick.

Will send v2.

> This whole command is really hard to read but I don't really see an
> obvious way to simplify it.

Yeah, the only part I think can be simplied is pre-expanding the value
after $(build)=, maybe ...

> 
> >  
> >  	rm -f "${destdir}/scripts/Kbuild"
> >  fi
> > 
> > ---
> > base-commit: 9c0826a5d9aa4d52206dd89976858457a2a8a7ed
> > change-id: 20251109-kbuild-install-extmod-build-fix-cc-expand-third-try-2cb1540cadbf
> > 
> > Best regards,
> > -- 
> > Abel Vesa <abel.vesa@...aro.org>
> >