[PATCH 1/3] kbuild: rpm-pkg: disable kernel-devel package when cross-compiling

[PATCH 1/3] kbuild: rpm-pkg: disable kernel-devel package when cross-compiling

[Masahiro Yamada]

Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package
when possible"), 'make binrpm-pkg' may attempt to cross-compile the
kernel-devel package, but it fails under certain circumstances.

For example, when CONFIG_MODULE_SIG_FORMAT is enabled on openSUSE
Tumbleweed, the following command fails:

  $ make ARCH=arm64 CROSS_COMPILE=aarch64-suse-linux- binrpm-pkg
      [ snip ]
  Rebuilding host programs with aarch64-suse-linux-gcc...
    HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/kallsyms
    HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/sorttable
    HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/asn1_compiler
    HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/sign-file
  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/sign-file.c:25:10: fatal error: openssl/opensslv.h: No such file or directory
     25 | #include <openssl/opensslv.h>
        |          ^~~~~~~~~~~~~~~~~~~~
  compilation terminated.

I believe this issue is less common on Fedora because cross-compiling
user-space programs is not possible, even if the gcc-aarch64-linux-gnu
package is installed. In other words, CONFIG_CC_CAN_LINK is unset.

On Fedora 40, the package information explains this limitation clearly:

  $ dnf info gcc-aarch64-linux-gnu
      [ snip ]
  Description  : Cross-build GNU C compiler.
               :
               : Only building kernels is currently supported.  Support for cross-building
               : user space programs is not currently provided as that would massively multiply
               : the number of packages.

This commit disables the kernel-devel package when cross-compiling
because cross-compiling RPM packages is somewhat challenging, and I
did not come up with a better solution.

Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/Makefile.package | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/Makefile.package b/scripts/Makefile.package
index 11d53f240a2b..b9a4b0c8b8a0 100644
--- a/scripts/Makefile.package
+++ b/scripts/Makefile.package
@@ -72,7 +72,8 @@ rpm-pkg srcrpm-pkg binrpm-pkg: rpmbuild/SPECS/kernel.spec
 	--define='_topdir $(abspath rpmbuild)' \
 	$(if $(filter a b, $(build-type)), \
 		--target $(UTS_MACHINE)-linux --build-in-place --noprep --define='_smp_mflags %{nil}' \
-		$$(rpm -q rpm >/dev/null 2>&1 || echo --nodeps)) \
+		$$(rpm -q rpm >/dev/null 2>&1 || echo --nodeps) \
+		$(if $(cross_compiling), --without=devel)) \
 	$(RPMOPTS))
 
 # deb-pkg srcdeb-pkg bindeb-pkg
-- 
2.43.0

[PATCH 2/3] kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

[Masahiro Yamada]

Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package
when possible"), 'make bindeb-pkg' may attempt to cross-compile the
linux-headers package, but it fails under certain circumstances.

For example, when CONFIG_MODULE_SIG_FORMAT is enabled on Debian, the
following command fails:

  $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
      [ snip ]
  Rebuilding host programs with aarch64-linux-gnu-gcc...
    HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/kallsyms
    HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sorttable
    HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/asn1_compiler
    HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file
  In file included from /usr/include/openssl/opensslv.h:109,
                   from debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file.c:25:
  /usr/include/openssl/macros.h:14:10: fatal error: openssl/opensslconf.h: No such file or directory
     14 | #include <openssl/opensslconf.h>
        |          ^~~~~~~~~~~~~~~~~~~~~~~
  compilation terminated.

This commit adds a new profile, pkg.linux-upstream.nokernelheaders, to
guard the linux-headers package.

There are two options to fix the above issue.

[option 1] Set the pkg.linux-upstream.nokernelheaders build profile

  $ DEB_BUILD_PROFILES=pkg.linux-upstream.nokernelheaders \
    make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg

This skips the building of the linux-headers package.

[option 2] Install the necessary build dependencies

If you want to cross-compile the linux-headers package, you need to
install additional packages. This is a one-time installation step.

For example, on Debian, the packages necessary for cross-compiling it
to arm64 can be installed with the following commands:

  # dpkg --add-architecture arm64
  # apt update
  # apt install gcc-aarch64-linux-gnu libssl-dev:arm64

Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible")
Reported-by: Ron Economos <re@w6rz.net>
Closes: https://lore.kernel.org/all/b3d4f49e-7ddb-29ba-0967-689232329b53@w6rz.net/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/package/builddeb             | 2 +-
 scripts/package/install-extmod-build | 6 ++----
 scripts/package/mkdebian             | 9 ++++++++-
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index 404587fc71fe..441b0bb66e0d 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -123,7 +123,7 @@ install_kernel_headers () {
 	pdir=debian/$1
 	version=${1#linux-headers-}
 
-	"${srctree}/scripts/package/install-extmod-build" "${pdir}/usr/src/linux-headers-${version}"
+	CC="${DEB_HOST_GNU_TYPE}-gcc" "${srctree}/scripts/package/install-extmod-build" "${pdir}/usr/src/linux-headers-${version}"
 
 	mkdir -p $pdir/lib/modules/$version/
 	ln -s /usr/src/linux-headers-$version $pdir/lib/modules/$version/build
diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build
index d2c9cacecc0c..7ec1f061a519 100755
--- a/scripts/package/install-extmod-build
+++ b/scripts/package/install-extmod-build
@@ -44,13 +44,11 @@ mkdir -p "${destdir}"
 	fi
 } | tar -c -f - -T - | tar -xf - -C "${destdir}"
 
-# When ${CC} and ${HOSTCC} differ, we are likely cross-compiling. Rebuild host
-# programs using ${CC}. This assumes CC=${CROSS_COMPILE}gcc, which is usually
-# the case for package building. It does not cross-compile when CC=clang.
+# When ${CC} and ${HOSTCC} differ, rebuild host programs using ${CC}.
 #
 # This caters to host programs that participate in Kbuild. objtool and
 # resolve_btfids are out of scope.
-if [ "${CC}" != "${HOSTCC}" ] && is_enabled CONFIG_CC_CAN_LINK; then
+if [ "${CC}" != "${HOSTCC}" ]; then
 	echo "Rebuilding host programs with ${CC}..."
 
 	cat <<-'EOF' >  "${destdir}/Kbuild"
diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
index 10637d403777..93eb50356ddb 100755
--- a/scripts/package/mkdebian
+++ b/scripts/package/mkdebian
@@ -179,6 +179,8 @@ fi
 
 echo $debarch > debian/arch
 
+host_gnu=$(dpkg-architecture -a "${debarch}" -q DEB_HOST_GNU_TYPE | sed 's/_/-/g')
+
 # Generate a simple changelog template
 cat <<EOF > debian/changelog
 $sourcename ($packageversion) $distribution; urgency=low
@@ -196,7 +198,11 @@ Priority: optional
 Maintainer: $maintainer
 Rules-Requires-Root: no
 Build-Depends: debhelper-compat (= 12)
-Build-Depends-Arch: bc, bison, cpio, flex, kmod, libelf-dev:native, libssl-dev:native, rsync
+Build-Depends-Arch: bc, bison, cpio, flex,
+ gcc-${host_gnu} <!pkg.${sourcename}.nokernelheaders>,
+ kmod, libelf-dev:native,
+ libssl-dev:native, libssl-dev <!pkg.${sourcename}.nokernelheaders>,
+ rsync
 Homepage: https://www.kernel.org/
 
 Package: $packagename-$version
@@ -224,6 +230,7 @@ cat <<EOF >> debian/control
 
 Package: linux-headers-$version
 Architecture: $debarch
+Build-Profiles: <!pkg.${sourcename}.nokernelheaders>
 Description: Linux kernel headers for $version on $debarch
  This package provides kernel header files for $version on $debarch
  .
-- 
2.43.0

[PATCH 3/3] kbuild: deb-pkg: add pkg.linux-upstream.nokerneldbg build profile

[Masahiro Yamada]

The Debian kernel supports the pkg.linux.nokerneldbg build profile.

The debug package tends to be huge, and you may not want to build it
even when CONFIG_DEBUG_INFO is enabled. This commit introduces a
similar profile for the upstream kernel.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/package/mkdebian | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
index 93eb50356ddb..fc3b7fa709fc 100755
--- a/scripts/package/mkdebian
+++ b/scripts/package/mkdebian
@@ -245,6 +245,7 @@ cat <<EOF >> debian/control
 Package: linux-image-$version-dbg
 Section: debug
 Architecture: $debarch
+Build-Profiles: <!pkg.${sourcename}.nokerneldbg>
 Description: Linux kernel debugging symbols for $version
  This package will come in handy if you need to debug the kernel. It provides
  all the necessary debug symbols for the kernel and its modules.
-- 
2.43.0

Re: [PATCH 2/3] kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

[Ron Economos]

On 10/22/24 11:16 AM, Masahiro Yamada wrote:
> Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package
> when possible"), 'make bindeb-pkg' may attempt to cross-compile the
> linux-headers package, but it fails under certain circumstances.
>
> For example, when CONFIG_MODULE_SIG_FORMAT is enabled on Debian, the
> following command fails:
>
>    $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
>        [ snip ]
>    Rebuilding host programs with aarch64-linux-gnu-gcc...
>      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/kallsyms
>      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sorttable
>      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/asn1_compiler
>      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file
>    In file included from /usr/include/openssl/opensslv.h:109,
>                     from debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file.c:25:
>    /usr/include/openssl/macros.h:14:10: fatal error: openssl/opensslconf.h: No such file or directory
>       14 | #include <openssl/opensslconf.h>
>          |          ^~~~~~~~~~~~~~~~~~~~~~~
>    compilation terminated.
>
> This commit adds a new profile, pkg.linux-upstream.nokernelheaders, to
> guard the linux-headers package.
>
> There are two options to fix the above issue.
>
> [option 1] Set the pkg.linux-upstream.nokernelheaders build profile
>
>    $ DEB_BUILD_PROFILES=pkg.linux-upstream.nokernelheaders \
>      make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
>
> This skips the building of the linux-headers package.
>
> [option 2] Install the necessary build dependencies
>
> If you want to cross-compile the linux-headers package, you need to
> install additional packages. This is a one-time installation step.
>
> For example, on Debian, the packages necessary for cross-compiling it
> to arm64 can be installed with the following commands:
>
>    # dpkg --add-architecture arm64
>    # apt update
>    # apt install gcc-aarch64-linux-gnu libssl-dev:arm64
>
> Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible")
> Reported-by: Ron Economos <re@w6rz.net>
> Closes: https://lore.kernel.org/all/b3d4f49e-7ddb-29ba-0967-689232329b53@w6rz.net/
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
>   scripts/package/builddeb             | 2 +-
>   scripts/package/install-extmod-build | 6 ++----
>   scripts/package/mkdebian             | 9 ++++++++-
>   3 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/scripts/package/builddeb b/scripts/package/builddeb
> index 404587fc71fe..441b0bb66e0d 100755
> --- a/scripts/package/builddeb
> +++ b/scripts/package/builddeb
> @@ -123,7 +123,7 @@ install_kernel_headers () {
>   	pdir=debian/$1
>   	version=${1#linux-headers-}
>   
> -	"${srctree}/scripts/package/install-extmod-build" "${pdir}/usr/src/linux-headers-${version}"
> +	CC="${DEB_HOST_GNU_TYPE}-gcc" "${srctree}/scripts/package/install-extmod-build" "${pdir}/usr/src/linux-headers-${version}"
>   
>   	mkdir -p $pdir/lib/modules/$version/
>   	ln -s /usr/src/linux-headers-$version $pdir/lib/modules/$version/build
> diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build
> index d2c9cacecc0c..7ec1f061a519 100755
> --- a/scripts/package/install-extmod-build
> +++ b/scripts/package/install-extmod-build
> @@ -44,13 +44,11 @@ mkdir -p "${destdir}"
>   	fi
>   } | tar -c -f - -T - | tar -xf - -C "${destdir}"
>   
> -# When ${CC} and ${HOSTCC} differ, we are likely cross-compiling. Rebuild host
> -# programs using ${CC}. This assumes CC=${CROSS_COMPILE}gcc, which is usually
> -# the case for package building. It does not cross-compile when CC=clang.
> +# When ${CC} and ${HOSTCC} differ, rebuild host programs using ${CC}.
>   #
>   # This caters to host programs that participate in Kbuild. objtool and
>   # resolve_btfids are out of scope.
> -if [ "${CC}" != "${HOSTCC}" ] && is_enabled CONFIG_CC_CAN_LINK; then
> +if [ "${CC}" != "${HOSTCC}" ]; then
>   	echo "Rebuilding host programs with ${CC}..."
>   
>   	cat <<-'EOF' >  "${destdir}/Kbuild"
> diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
> index 10637d403777..93eb50356ddb 100755
> --- a/scripts/package/mkdebian
> +++ b/scripts/package/mkdebian
> @@ -179,6 +179,8 @@ fi
>   
>   echo $debarch > debian/arch
>   
> +host_gnu=$(dpkg-architecture -a "${debarch}" -q DEB_HOST_GNU_TYPE | sed 's/_/-/g')
> +
>   # Generate a simple changelog template
>   cat <<EOF > debian/changelog
>   $sourcename ($packageversion) $distribution; urgency=low
> @@ -196,7 +198,11 @@ Priority: optional
>   Maintainer: $maintainer
>   Rules-Requires-Root: no
>   Build-Depends: debhelper-compat (= 12)
> -Build-Depends-Arch: bc, bison, cpio, flex, kmod, libelf-dev:native, libssl-dev:native, rsync
> +Build-Depends-Arch: bc, bison, cpio, flex,
> + gcc-${host_gnu} <!pkg.${sourcename}.nokernelheaders>,
> + kmod, libelf-dev:native,
> + libssl-dev:native, libssl-dev <!pkg.${sourcename}.nokernelheaders>,
> + rsync
>   Homepage: https://www.kernel.org/
>   
>   Package: $packagename-$version
> @@ -224,6 +230,7 @@ cat <<EOF >> debian/control
>   
>   Package: linux-headers-$version
>   Architecture: $debarch
> +Build-Profiles: <!pkg.${sourcename}.nokernelheaders>
>   Description: Linux kernel headers for $version on $debarch
>    This package provides kernel header files for $version on $debarch
>    .

Tested with option 2 for RISC-V. On Ubuntu 24.04, the following must be 
added to the file /etc/apt/sources.list.d/ubuntu.sources for apt update 
to fetch the correct repositories:

Types: deb
URIs: http://ports.ubuntu.com/ubuntu-ports
Suites: noble noble-updates noble-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
Architectures: riscv64

Then:

sudo dpkg --add-architecture riscv64
sudo apt-get update
sudo apt-get install libssl-dev:riscv64

The tool chain at https://github.com/riscv-collab/riscv-gnu-toolchain 
can also be made to work. See:

https://github.com/riscv-collab/riscv-gnu-toolchain/issues/1590

Tested-by: Ron Economos <re@w6rz.net>

Re: [PATCH 2/3] kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

[Masahiro Yamada]

On Wed, Oct 23, 2024 at 10:06 PM Ron Economos <re@w6rz.net> wrote:
>
> On 10/22/24 11:16 AM, Masahiro Yamada wrote:
> > Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package
> > when possible"), 'make bindeb-pkg' may attempt to cross-compile the
> > linux-headers package, but it fails under certain circumstances.
> >
> > For example, when CONFIG_MODULE_SIG_FORMAT is enabled on Debian, the
> > following command fails:
> >
> >    $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
> >        [ snip ]
> >    Rebuilding host programs with aarch64-linux-gnu-gcc...
> >      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/kallsyms
> >      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sorttable
> >      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/asn1_compiler
> >      HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file
> >    In file included from /usr/include/openssl/opensslv.h:109,
> >                     from debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file.c:25:
> >    /usr/include/openssl/macros.h:14:10: fatal error: openssl/opensslconf.h: No such file or directory
> >       14 | #include <openssl/opensslconf.h>
> >          |          ^~~~~~~~~~~~~~~~~~~~~~~
> >    compilation terminated.
> >
> > This commit adds a new profile, pkg.linux-upstream.nokernelheaders, to
> > guard the linux-headers package.
> >
> > There are two options to fix the above issue.
> >
> > [option 1] Set the pkg.linux-upstream.nokernelheaders build profile
> >
> >    $ DEB_BUILD_PROFILES=pkg.linux-upstream.nokernelheaders \
> >      make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
> >
> > This skips the building of the linux-headers package.
> >
> > [option 2] Install the necessary build dependencies
> >
> > If you want to cross-compile the linux-headers package, you need to
> > install additional packages. This is a one-time installation step.
> >
> > For example, on Debian, the packages necessary for cross-compiling it
> > to arm64 can be installed with the following commands:
> >
> >    # dpkg --add-architecture arm64
> >    # apt update
> >    # apt install gcc-aarch64-linux-gnu libssl-dev:arm64
> >
> > Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible")
> > Reported-by: Ron Economos <re@w6rz.net>
> > Closes: https://lore.kernel.org/all/b3d4f49e-7ddb-29ba-0967-689232329b53@w6rz.net/
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
> >
> >   scripts/package/builddeb             | 2 +-
> >   scripts/package/install-extmod-build | 6 ++----
> >   scripts/package/mkdebian             | 9 ++++++++-
> >   3 files changed, 11 insertions(+), 6 deletions(-)
> >
> > diff --git a/scripts/package/builddeb b/scripts/package/builddeb
> > index 404587fc71fe..441b0bb66e0d 100755
> > --- a/scripts/package/builddeb
> > +++ b/scripts/package/builddeb
> > @@ -123,7 +123,7 @@ install_kernel_headers () {
> >       pdir=debian/$1
> >       version=${1#linux-headers-}
> >
> > -     "${srctree}/scripts/package/install-extmod-build" "${pdir}/usr/src/linux-headers-${version}"
> > +     CC="${DEB_HOST_GNU_TYPE}-gcc" "${srctree}/scripts/package/install-extmod-build" "${pdir}/usr/src/linux-headers-${version}"
> >
> >       mkdir -p $pdir/lib/modules/$version/
> >       ln -s /usr/src/linux-headers-$version $pdir/lib/modules/$version/build
> > diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build
> > index d2c9cacecc0c..7ec1f061a519 100755
> > --- a/scripts/package/install-extmod-build
> > +++ b/scripts/package/install-extmod-build
> > @@ -44,13 +44,11 @@ mkdir -p "${destdir}"
> >       fi
> >   } | tar -c -f - -T - | tar -xf - -C "${destdir}"
> >
> > -# When ${CC} and ${HOSTCC} differ, we are likely cross-compiling. Rebuild host
> > -# programs using ${CC}. This assumes CC=${CROSS_COMPILE}gcc, which is usually
> > -# the case for package building. It does not cross-compile when CC=clang.
> > +# When ${CC} and ${HOSTCC} differ, rebuild host programs using ${CC}.
> >   #
> >   # This caters to host programs that participate in Kbuild. objtool and
> >   # resolve_btfids are out of scope.
> > -if [ "${CC}" != "${HOSTCC}" ] && is_enabled CONFIG_CC_CAN_LINK; then
> > +if [ "${CC}" != "${HOSTCC}" ]; then
> >       echo "Rebuilding host programs with ${CC}..."
> >
> >       cat <<-'EOF' >  "${destdir}/Kbuild"
> > diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
> > index 10637d403777..93eb50356ddb 100755
> > --- a/scripts/package/mkdebian
> > +++ b/scripts/package/mkdebian
> > @@ -179,6 +179,8 @@ fi
> >
> >   echo $debarch > debian/arch
> >
> > +host_gnu=$(dpkg-architecture -a "${debarch}" -q DEB_HOST_GNU_TYPE | sed 's/_/-/g')
> > +
> >   # Generate a simple changelog template
> >   cat <<EOF > debian/changelog
> >   $sourcename ($packageversion) $distribution; urgency=low
> > @@ -196,7 +198,11 @@ Priority: optional
> >   Maintainer: $maintainer
> >   Rules-Requires-Root: no
> >   Build-Depends: debhelper-compat (= 12)
> > -Build-Depends-Arch: bc, bison, cpio, flex, kmod, libelf-dev:native, libssl-dev:native, rsync
> > +Build-Depends-Arch: bc, bison, cpio, flex,
> > + gcc-${host_gnu} <!pkg.${sourcename}.nokernelheaders>,
> > + kmod, libelf-dev:native,
> > + libssl-dev:native, libssl-dev <!pkg.${sourcename}.nokernelheaders>,
> > + rsync
> >   Homepage: https://www.kernel.org/
> >
> >   Package: $packagename-$version
> > @@ -224,6 +230,7 @@ cat <<EOF >> debian/control
> >
> >   Package: linux-headers-$version
> >   Architecture: $debarch
> > +Build-Profiles: <!pkg.${sourcename}.nokernelheaders>
> >   Description: Linux kernel headers for $version on $debarch
> >    This package provides kernel header files for $version on $debarch
> >    .
>
> Tested with option 2 for RISC-V. On Ubuntu 24.04, the following must be
> added to the file /etc/apt/sources.list.d/ubuntu.sources for apt update
> to fetch the correct repositories:
>
> Types: deb
> URIs: http://ports.ubuntu.com/ubuntu-ports
> Suites: noble noble-updates noble-backports
> Components: main universe restricted multiverse
> Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
> Architectures: riscv64

Right, this is an annoyance of Ubuntu.

x86 and non-x86 architectures use different repositories.



>
> Then:
>
> sudo dpkg --add-architecture riscv64
> sudo apt-get update
> sudo apt-get install libssl-dev:riscv64
>
> The tool chain at https://github.com/riscv-collab/riscv-gnu-toolchain
> can also be made to work. See:
>
> https://github.com/riscv-collab/riscv-gnu-toolchain/issues/1590


You can use any toolchain.

The linux-headers package is rebuilt with riscv64-linux-gnu-gcc,
not your own toolchain.



> Tested-by: Ron Economos <re@w6rz.net>
>
>


-- 
Best Regards
Masahiro Yamada

Re: [PATCH 2/3] kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

[Nicolas Schier]

On Wed, Oct 23, 2024 at 03:16:58AM +0900 Masahiro Yamada wrote:
> Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package
> when possible"), 'make bindeb-pkg' may attempt to cross-compile the
> linux-headers package, but it fails under certain circumstances.
> 
> For example, when CONFIG_MODULE_SIG_FORMAT is enabled on Debian, the
> following command fails:
> 
>   $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
>       [ snip ]
>   Rebuilding host programs with aarch64-linux-gnu-gcc...
>     HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/kallsyms
>     HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sorttable
>     HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/asn1_compiler
>     HOSTCC  debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file
>   In file included from /usr/include/openssl/opensslv.h:109,
>                    from debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file.c:25:
>   /usr/include/openssl/macros.h:14:10: fatal error: openssl/opensslconf.h: No such file or directory
>      14 | #include <openssl/opensslconf.h>
>         |          ^~~~~~~~~~~~~~~~~~~~~~~
>   compilation terminated.
> 
> This commit adds a new profile, pkg.linux-upstream.nokernelheaders, to
> guard the linux-headers package.
> 
> There are two options to fix the above issue.
> 
> [option 1] Set the pkg.linux-upstream.nokernelheaders build profile
> 
>   $ DEB_BUILD_PROFILES=pkg.linux-upstream.nokernelheaders \
>     make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg
> 
> This skips the building of the linux-headers package.
> 
> [option 2] Install the necessary build dependencies
> 
> If you want to cross-compile the linux-headers package, you need to
> install additional packages. This is a one-time installation step.
> 
> For example, on Debian, the packages necessary for cross-compiling it
> to arm64 can be installed with the following commands:
> 
>   # dpkg --add-architecture arm64
>   # apt update
>   # apt install gcc-aarch64-linux-gnu libssl-dev:arm64
> 
> Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible")
> Reported-by: Ron Economos <re@w6rz.net>
> Closes: https://lore.kernel.org/all/b3d4f49e-7ddb-29ba-0967-689232329b53@w6rz.net/
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>  scripts/package/builddeb             | 2 +-
>  scripts/package/install-extmod-build | 6 ++----
>  scripts/package/mkdebian             | 9 ++++++++-
>  3 files changed, 11 insertions(+), 6 deletions(-)

Nice solution and thanks for also documenting option 2.

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Re: [PATCH 3/3] kbuild: deb-pkg: add pkg.linux-upstream.nokerneldbg build profile

[Nicolas Schier]

On Wed, Oct 23, 2024 at 03:16:59AM +0900 Masahiro Yamada wrote:
> The Debian kernel supports the pkg.linux.nokerneldbg build profile.
> 
> The debug package tends to be huge, and you may not want to build it
> even when CONFIG_DEBUG_INFO is enabled. This commit introduces a
> similar profile for the upstream kernel.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>  scripts/package/mkdebian | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
> index 93eb50356ddb..fc3b7fa709fc 100755
> --- a/scripts/package/mkdebian
> +++ b/scripts/package/mkdebian
> @@ -245,6 +245,7 @@ cat <<EOF >> debian/control
>  Package: linux-image-$version-dbg
>  Section: debug
>  Architecture: $debarch
> +Build-Profiles: <!pkg.${sourcename}.nokerneldbg>
>  Description: Linux kernel debugging symbols for $version
>   This package will come in handy if you need to debug the kernel. It provides
>   all the necessary debug symbols for the kernel and its modules.
> -- 
> 2.43.0
> 
> 

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Re: [PATCH 1/3] kbuild: rpm-pkg: disable kernel-devel package when cross-compiling

[Nathan Chancellor]

On Wed, Oct 23, 2024 at 03:16:57AM +0900, Masahiro Yamada wrote:
> Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package
> when possible"), 'make binrpm-pkg' may attempt to cross-compile the
> kernel-devel package, but it fails under certain circumstances.
> 
> For example, when CONFIG_MODULE_SIG_FORMAT is enabled on openSUSE
> Tumbleweed, the following command fails:
> 
>   $ make ARCH=arm64 CROSS_COMPILE=aarch64-suse-linux- binrpm-pkg
>       [ snip ]
>   Rebuilding host programs with aarch64-suse-linux-gcc...
>     HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/kallsyms
>     HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/sorttable
>     HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/asn1_compiler
>     HOSTCC  /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/sign-file
>   /home/masahiro/ref/linux/rpmbuild/BUILDROOT/kernel-6.12.0_rc4-1.aarch64/usr/src/kernels/6.12.0-rc4/scripts/sign-file.c:25:10: fatal error: openssl/opensslv.h: No such file or directory
>      25 | #include <openssl/opensslv.h>
>         |          ^~~~~~~~~~~~~~~~~~~~
>   compilation terminated.
> 
> I believe this issue is less common on Fedora because cross-compiling
> user-space programs is not possible, even if the gcc-aarch64-linux-gnu
> package is installed. In other words, CONFIG_CC_CAN_LINK is unset.
> 
> On Fedora 40, the package information explains this limitation clearly:
> 
>   $ dnf info gcc-aarch64-linux-gnu
>       [ snip ]
>   Description  : Cross-build GNU C compiler.
>                :
>                : Only building kernels is currently supported.  Support for cross-building
>                : user space programs is not currently provided as that would massively multiply
>                : the number of packages.
> 
> This commit disables the kernel-devel package when cross-compiling
> because cross-compiling RPM packages is somewhat challenging, and I
> did not come up with a better solution.
> 
> Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible")
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> 
>  scripts/Makefile.package | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.package b/scripts/Makefile.package
> index 11d53f240a2b..b9a4b0c8b8a0 100644
> --- a/scripts/Makefile.package
> +++ b/scripts/Makefile.package
> @@ -72,7 +72,8 @@ rpm-pkg srcrpm-pkg binrpm-pkg: rpmbuild/SPECS/kernel.spec
>  	--define='_topdir $(abspath rpmbuild)' \
>  	$(if $(filter a b, $(build-type)), \
>  		--target $(UTS_MACHINE)-linux --build-in-place --noprep --define='_smp_mflags %{nil}' \
> -		$$(rpm -q rpm >/dev/null 2>&1 || echo --nodeps)) \
> +		$$(rpm -q rpm >/dev/null 2>&1 || echo --nodeps) \
> +		$(if $(cross_compiling), --without=devel)) \
>  	$(RPMOPTS))
>  
>  # deb-pkg srcdeb-pkg bindeb-pkg
> -- 
> 2.43.0
> 

Re: [PATCH 2/3] kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

[Matt Fleming]

Hey there,

Can you explain how this change works a bit more? This reads like it's now
impossible to build the debian linux-headers package with clang? At Cloudflare,
we're using a custom build of gcc, not the gcc-x86-64-linux-gnu package, and
with this change we can no longer build linux-headers.

What's the solution for those of us that want to build the linux-headers deb
package but can't install gcc-*-linux-gnu?

Re: [PATCH 2/3] kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

[Masahiro Yamada]

On Thu, Nov 7, 2024 at 4:18 AM Matt Fleming <matt@readmodwrite.com> wrote:
>
>
> Hey there,
>
> Can you explain how this change works a bit more? This reads like it's now
> impossible to build the debian linux-headers package with clang? At Cloudflare,
> we're using a custom build of gcc, not the gcc-x86-64-linux-gnu package, and
> with this change we can no longer build linux-headers.

You need to install the gcc-x86-64-linux-gnu package.
This is available on both Debian and Ubuntu.

Adding the prefix is required to reliably produce the correct
linux-headers package.

For example, when building a linux-headers package for i386 on amd64,
userspace tools must be recompiled with 'i686-linux-gnu-gcc'.


> What's the solution for those of us that want to build the linux-headers deb
> package but can't install gcc-*-linux-gnu?

DPKG_FLAGS=-d

will skip the build dependency check, but 'x86_64-linux-gnu-gcc'
is still required.

If only clang is available on your system, you need a workaround,
e.g.

 ln -s clang ~/bin/x86_64-linux-gnu-gcc

Anyway, you need to find a solution.

-- 
Best Regards
Masahiro Yamada