[Buildroot] Issue with the HOST_DIR/usr -> HOST_DIR move

[Arnout Vandecappelle <arnout@mind.be>]

On 09-07-17 18:25, Thomas Petazzoni wrote:
> Hello Arnout,
> 
> I've started rebuilding the pre-built Buildroot external toolchains
> after the HOST_DIR/usr -> HOST_DIR move. I've dropped my hack on the
> toolchain wrapper to support the fact that I was moving the toolchain
> out of the usr/ folder... because obviously this is no longer needed.
> So basically, I'm building on top of master + a patch that builds
> host-flex, host-gmp, host-mpc, etc. as static libraries instead of
> shared ones.
> 
> Using this defconfig:
> 
> BR2_arm=y
> BR2_HOST_DIR="/opt/br-arm-full-2017.05-1071-gef605f5"
> BR2_JLEVEL=16
> BR2_KERNEL_HEADERS_3_10=y
> BR2_TOOLCHAIN_BUILDROOT_LOCALE=y
> BR2_GCC_VERSION_4_9_X=y
> BR2_TOOLCHAIN_BUILDROOT_CXX=y
> BR2_INIT_NONE=y
> BR2_SYSTEM_BIN_SH_NONE=y
> # BR2_PACKAGE_BUSYBOX is not set
> # BR2_TARGET_ROOTFS_TAR is not set
> 
> I'm seeing this build failure:
> 
> ESC[7m>>> uclibc 1.0.25 BuildingESC[27m
> /usr/bin/make -j16 -C /opt/toolchain-build/build/uclibc-1.0.25 ARCH="arm" CROSS_COMPILE="/opt/br-arm-full-2017.05-1071-gef605f5/bin/arm-buildroot-linux-uclibcgnueabi-" UCLIBC_EXTRA_CFLAGS=" " HOSTCC="/usr/bin/gcc" headers
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> make[1]: Entering directory `/opt/toolchain-build/build/uclibc-1.0.25'
>   MKDIR include/bits
>   GEN include/bits/uClibc_config.h
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
>   LN include/semaphore.h
>   LN include/pthread.h
>   LN include/bits/libc-lock.h
>   LN include/bits/stdio-lock.h
>   LN include/bits/pthreadtypes.h
>   LN include/bits/semaphore.h
>   GEN include/bits/sysnum.h
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> /opt/br-arm-full-2017.05-1071-gef605f5/usr/bin/arm-buildroot-linux-uclibcgnueabi-gcc.br_real: No such file or directory
> 
> There are two problems here:
> 
>  * First, the problem that $(HOST_DIR)/usr didn't exist. The reason is
>    that you rule that creates $(HOST_DIR)/usr is only triggered if the
>    Buildroot Makefile creates $(HOST_DIR). But when you're building a
>    SDK inside /opt/foo/, therefore setting BR2_HOST_DIR=/opt/foo/, it's
>    pretty likely that /opt/foo/ might exist before Buildroot gets
>    triggered. In such a situation, your $(HOST_DIR) rule in the main
>    Makefile doesn't get triggered, and $(HOST_DIR)/usr is not created.

 I never thought of that - I assumed that the HOST_DIR would always be created
by Buildroot. But indeed it does make sense to install a toolchain in a
pre-existing directory.

 There is one problem with that, though: in such a situation, it is also
possible that the usr/ directory already exists, so we can't create the
compatibility symlink. I guess we'll just have to live with that.

 I'll make an explicit rule for $(HOST_DIR)/usr to solve this.



>  * Even if the symlink doesn't exist, the build should still work.
>    Indeed, the symlink was kept for backward compatibility reasons, but
>    here I'm doing a full build from scratch, which I would expect to
>    work even without the usr/ compatibility symlink.

 D'oh, this is really, really weird, I'm sure I looked at that piece of code
when I made my initial version of the series, but apparently I didn't look at it
again last week. There are still *three* references to $(HOST_DIR)/usr in
toolchain-wrapper.c...


 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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