From mboxrd@z Thu Jan  1 00:00:00 1970
From: Khem Raj <raj.khem@gmail.com>
Date: Tue, 3 Nov 2020 12:25:25 -0800
Subject: [Buildroot] [PATCH] external-toolchain: Detect linux/version.h
 via cross compiler
In-Reply-To: <20201103201640.GI2887157@scaer>
References: <20201023093641.619746-1-raj.khem@gmail.com>
 <20201103201640.GI2887157@scaer>
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On Tue, Nov 3, 2020 at 12:16 PM Yann E. MORIN <yann.morin.1998@free.fr> wrote:
>
> Khem, All,
>
> On 2020-10-23 02:36 -0700, Khem Raj spake thusly:
> > Using linux/version.h is assumed to be hardcoded inside sysroot but this
> > does not consider the case where toolchains might be built with
> > --with-native-system-header-dir which means the header directories will
> > not be under <sysroot>/usr/include but customized, archlinux, debian
> > built cross toolchains use these install settings ( due to multiarch )
> > they have the headers installed like /usr/aarch64-linux-gnu/include and
> > not /usr/aarch64-linux-gnu/usr/include
> >
> > This patch adds logic to use cross compiler to compute the path to
> > linux/version.h on the fly, it means we do not really need to assume the
> > install structure
> >
> > Fixes built when using external toolchains provided by archlinux e.g.
>
> So, to summarise our previous discussion on IRC the other day:
>
>   - Buildroot does not officially support distributions' cross
>     toolchains, as they may contain extra libraries that are not
>     accoutned for by Buildroot,
>

yes that's fine, this patch does not claim to support all of them
either, it just
makes the situation a bit better without regressing the supported usecases
I think it helps lowering the build times on such distros for
developers and improve
first time experience

>   - those toolchains are also not always relocatable, even if some
>     might be.

right and in this case, they are working ok I tried with archlinux
aarch64-linux-gnu-gcc package
and it worked well, debian also worked ok

>
> Also, Thomas since replied with further questionning, so we really need
> a bit more details in there, and how you manage to make it work.
>

right I have tried to clarify, feel free to ask more.

> Regards,
> Yann E. MORIN.
>
> > Signed-off-by: Khem Raj <raj.khem@gmail.com>
> > Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> > ---
> >  support/scripts/check-kernel-headers.sh           | 15 ++++++++++++++-
> >  toolchain/helpers.mk                              |  2 +-
> >  .../toolchain-external/pkg-toolchain-external.mk  |  3 ++-
> >  3 files changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/support/scripts/check-kernel-headers.sh b/support/scripts/check-kernel-headers.sh
> > index 4e6dce5487..5cedb9a082 100755
> > --- a/support/scripts/check-kernel-headers.sh
> > +++ b/support/scripts/check-kernel-headers.sh
> > @@ -21,6 +21,9 @@ SYSROOT="${2}"
> >  HDR_VER="${3}.0.0"
> >  CHECK="${4}"  # 'strict' or 'loose'
> >
> > +# cross compiler passed in case of external toolchains
> > +CROSS_CC="${5}"
> > +
> >  HDR_M="${HDR_VER%%.*}"
> >  HDR_V="${HDR_VER#*.}"
> >  HDR_m="${HDR_V%%.*}"
> > @@ -36,11 +39,21 @@ trap 'rm -f "${EXEC}"' EXIT
> >
> >  EXEC="$(mktemp -p "${BUILDDIR}" -t .check-headers.XXXXXX)"
> >
> > +if [ -n "${CROSS_CC}" ]; then
> > +  MAKE_VER_H=$(${CROSS_CC} -M -xc - <<_EOF_
> > +#include <linux/version.h>
> > +_EOF_
> > +  )
> > +  VER_H=`echo $MAKE_VER_H | awk 'END {print $NF}'`
> > +else
> > +  VER_H="${SYSROOT}/usr/include/linux/version.h"
> > +fi
> > +
> >  # We do not want to account for the patch-level, since headers are
> >  # not supposed to change for different patchlevels, so we mask it out.
> >  # This only applies to kernels >= 3.0, but those are the only one
> >  # we actually care about; we treat all 2.6.x kernels equally.
> > -${HOSTCC} -imacros "${SYSROOT}/usr/include/linux/version.h" \
> > +${HOSTCC} -imacros "${VER_H}" \
> >            -x c -o "${EXEC}" - <<_EOF_
> >  #include <stdio.h>
> >  #include <stdlib.h>
> > diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
> > index 17bc159f3e..51d840b176 100644
> > --- a/toolchain/helpers.mk
> > +++ b/toolchain/helpers.mk
> > @@ -166,7 +166,7 @@ copy_toolchain_sysroot = \
> >  #
> >  check_kernel_headers_version = \
> >       if ! support/scripts/check-kernel-headers.sh $(1) $(2) $(3) \
> > -             $(if $(BR2_TOOLCHAIN_HEADERS_LATEST),$(4),strict); \
> > +             $(if $(BR2_TOOLCHAIN_HEADERS_LATEST),$(4),strict) $(5); \
> >       then \
> >               exit 1; \
> >       fi
> > diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
> > index 6d91cb5d1e..93f725dada 100644
> > --- a/toolchain/toolchain-external/pkg-toolchain-external.mk
> > +++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
> > @@ -549,7 +549,8 @@ define $(2)_CONFIGURE_CMDS
> >               $$(BUILD_DIR),\
> >               $$(call toolchain_find_sysroot,$$(TOOLCHAIN_EXTERNAL_CC)),\
> >               $$(call qstrip,$$(BR2_TOOLCHAIN_HEADERS_AT_LEAST)),\
> > -             $$(if $$(BR2_TOOLCHAIN_EXTERNAL_CUSTOM),loose,strict)); \
> > +             $$(if $$(BR2_TOOLCHAIN_EXTERNAL_CUSTOM),loose,strict),\
> > +             $$(TOOLCHAIN_EXTERNAL_CC)); \
> >       $$(call check_gcc_version,$$(TOOLCHAIN_EXTERNAL_CC),\
> >               $$(call qstrip,$$(BR2_TOOLCHAIN_GCC_AT_LEAST))); \
> >       if test "$$(BR2_arm)" = "y" ; then \
> > --
> > 2.29.0
> >
> > _______________________________________________
> > buildroot mailing list
> > buildroot at busybox.net
> > http://lists.busybox.net/mailman/listinfo/buildroot
>
> --
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