linux-kernel - Re: [PATCH 1/3] kbuild: deb-pkg: do not query DEB_HOST

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Date: Tue, 26 Dec 2023 14:34:25 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Masahiro Yamada <masahiroy@...nel.org>, linux-kbuild@...r.kernel.org, 
	Ben Hutchings <ben@...adent.org.uk>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, linux-kernel@...r.kernel.org
Cc: Nicolas Schier <nicolas@...sle.eu>
Subject: Re: [PATCH 1/3] kbuild: deb-pkg: do not query DEB_HOST_MULTIARCH

On Fri, Dec 22, 2023 at 11:30 PM Nicolas Schier <n.schier@....de> wrote:
>
> On Wed, Dec 20, 2023 at 03:19:55AM +0900, Masahiro Yamada wrote:
> > Since commit 491b146d4c13 ("kbuild: builddeb: Eliminate debian/arch
> > use"), the direct execution of debian/rules fails with:
> >
> >   dpkg-architecture: error: unknown option 'DEB_HOST_MULTIARCH'
> >
> > I am not sure how important to support such a use case, but at least
> > the current code:
> >
> >   dpkg-architecture -a$DEB_HOST_ARCH -qDEB_HOST_MULTIARCH
> >
> > ... looks weird because:
> >
> >  - For this code to work correctly, DEB_HOST_ARCH must be defined.
> >    In this case, DEB_HOST_MULTIARCH is likely defined, so there is no
> >    need to query DEB_HOST_MULTIARCH in the first place. This is likely
> >    the case where the package build was initiated by dpkg-buildpackage.
> >
> >  - If DEB_HOST_MULTIARCH is undefined, DEB_HOST_ARCH is likely undefined.
> >    So, you cannot query DEB_HOST_MULTIARCH in this way. This is mostly
> >    the case where debian/rules is directly executed.
> >
> > If we want to run debian/rules directly, we can revert 491b146d4c13 or
> > add code to remember DEB_HOST_MULTIARCH, but I chose to remove the
> > useless code for now.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > ---
>
> thanks.  Fixing the non-functional things is obviously a good thing.
>
> Reviewed-by: Nicolas Schier <n.schier@....de>
>
>
> Iff we'd like to be able to call debian/rules directly, do we really
> have to remember DEB_HOST_MULTIARCH, or just DEB_HOST_ARCH?


Theoretically, if we know DEB_HOST_ARCH,
other DEB_HOST_* can be derived.


scripts/package/deb-build-option needs to know more DEB_* variables.

  DEB_HOST_ARCH
  DEB_BUILD_ARCH
  DEB_HOST_GNU_TYPE









>
> In the latter case, might this be a sufficient way to allow calling
> debian/rules again?


Not perfectly.
scripts/package/deb-build-option does not work as intended.


>
> diff --git a/scripts/package/debian/rules b/scripts/package/debian/rules
> index 3dafa9496c63..e3e0001e7556 100755
> --- a/scripts/package/debian/rules
> +++ b/scripts/package/debian/rules
> @@ -3,7 +3,9 @@
>
>  include debian/rules.vars
>
> -srctree ?= .
> +DEB_HOST_ARCH ?= $(shell cat debian/arch)
> +
> +srctree ?= $(or $(wildcard source), .)
>
>  ifneq (,$(filter-out parallel=1,$(filter parallel=%,$(DEB_BUILD_OPTIONS))))
>      NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
>
>
> ... but the more I think about it, I am not convinced that we want to
> use the debian/arch file.  Actually I think it would be nice if we
> strive for an architecture independent source package instead of
> engraving the architecture even more.


The source package _is_ arch-independent,
can be built for a single architecture because
the source package for upstream contains the .config,
which is configured for a particular architecture.







>
> Nevertheless, your patch looks good to me.
>
> Kind regards,
> Nicolas
>
>
>
> >
> >  scripts/package/builddeb | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/scripts/package/builddeb b/scripts/package/builddeb
> > index 2fe51e6919da..2eb4910f0ef3 100755
> > --- a/scripts/package/builddeb
> > +++ b/scripts/package/builddeb
> > @@ -171,9 +171,8 @@ install_libc_headers () {
> >
> >       # move asm headers to /usr/include/<libc-machine>/asm to match the structure
> >       # used by Debian-based distros (to support multi-arch)
> > -     host_arch=$(dpkg-architecture -a$DEB_HOST_ARCH -qDEB_HOST_MULTIARCH)
> > -     mkdir $pdir/usr/include/$host_arch
> > -     mv $pdir/usr/include/asm $pdir/usr/include/$host_arch/
> > +     mkdir "$pdir/usr/include/${DEB_HOST_MULTIARCH}"
> > +     mv "$pdir/usr/include/asm" "$pdir/usr/include/${DEB_HOST_MULTIARCH}"
> >  }
> >
> >  rm -f debian/files
> > --
> > 2.40.1
> >



-- 
Best Regards
Masahiro Yamada