[Buildroot] [PATCH 1/1] Fix elf2flt build

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Douglas,

Please do not reply to me directly: keep the list in Cc so that others
can continue to participate to the discussion. Thanks!

On Thu, 27 Aug 2015 20:56:42 +0200, Douglas RAILLARD wrote:
> Thomas,
> 
> > Thanks for this patch. Great to see that there is some interest in
> > noMMU architecture. Which architecture are you working on?
> 
> Im actually working on the STM32F429 Cortex M4 with the
> stm32f429-discovery board from STMicroelectronics.

Nice!

> It seems that things are also moving on the kernel side
> for this arch and board.

Yes, ST is pushing patches to the upstream kernel for this platform.

> > I'm not able to reproduce the problem: here host-elf2flt builds fine.
> 
> I did not find any failure for elf2flt on the autobuild server,
> but without the patch, make complains.
> I have not checked if libbfd can be configured without plugin
> support, but it fails with my configuration
> (sorry for untranslated french diagnostic error):
> /usr/bin/gcc -Wall -O2 -I/working_dir/buildroot/output/host/usr/include -L/working_dir/buildroot/output/host/lib -L/working_dir/buildroot/output/host/usr/lib -Wl,-rpath,/working_dir/buildroot/output/host/usr/lib -o elf2flt elf2flt.o compress.o stubs.o -lc -lz /working_dir/buildroot/output/build/host-binutils-2.24/bfd/libbfd.a /working_dir/buildroot/output/build/host-binutils-2.24/libiberty/libiberty.a -lz
> /working_dir/buildroot/output/build/host-binutils-2.24/bfd/libbfd.a(plugin.o): in fonction ? try_load_plugin ?:
> plugin.c:(.text+0x1db): undefined reference to ? dlopen ?
> plugin.c:(.text+0x1f1): undefined reference to ? dlsym ?
> plugin.c:(.text+0x270): undefined reference to ? dlerror ?
> collect2: error: ld a retourn? 1 code d'?tat d'ex?cution
> Makefile:75 : la recette pour la cible ? elf2flt ? a ?chou?e
> make[1]: *** [elf2flt] Erreur 1
> make[1] : on quitte le r?pertoire ? /working_dir/buildroot/output/build/host-elf2flt-21c6a41885ad544763ccd19883c1353f3b0b7a47 ?

I have not reproduced this issue, but it might be caused by the fact
that you've enabled LTO support in gcc. I'll try again with LTO
enabled, just to narrow down the problem.

> > However the build of an ARM Cortex-M3 toolchain fails during the uClibc
> > build (which takes place *after* host-elf2flt is built).
> 
> There are indeed problems when some toolchain options are selected, 
> so I managed to leave them out for the moment to focus on getting 
> something built. Here is my buildroot configuration generated with
> make savedefconfig:
> BR2_arm=y
> BR2_cortex_m3=y
> BR2_ARM_INSTRUCTIONS_THUMB2=y
> BR2_GLOBAL_PATCH_DIR="../patch"
> BR2_UCLIBC_VERSION_0_9_33=y
> BR2_UCLIBC_CONFIG="package/uclibc/uClibc-ng.config"

This seems weird: using uClibc 0.9.33 with the configuration file for
uClibc-ng. Have you had any problem with uClibc-ng that made you go
back to uClibc 0.9.33 ?

> BR2_TOOLCHAIN_BUILDROOT_INET_RPC=y
> BR2_TOOLCHAIN_BUILDROOT_WCHAR=y
> BR2_PTHREADS_NONE=y

Any reason to disable thread support?

> BR2_TOOLCHAIN_BUILDROOT_USE_SSP=y
> BR2_GCC_ENABLE_LTO=y
> BR2_PACKAGE_HOST_ELF2FLT=y
> BR2_PACKAGE_HOST_GDB=y
> BR2_PACKAGE_HOST_GDB_TUI=y
> BR2_PACKAGE_HOST_GDB_PYTHON=y
> BR2_LINUX_KERNEL=y
> BR2_LINUX_KERNEL_CUSTOM_GIT=y
> BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git"
> BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="master"
> BR2_LINUX_KERNEL_DEFCONFIG="stm32"
> BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM=y
> BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="xipImage"
> BR2_TARGET_ROOTFS_ROMFS=y
> # BR2_TARGET_ROOTFS_TAR is not set
> BR2_TARGET_UBOOT=y
> BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
> BR2_TARGET_UBOOT_BOARD_DEFCONFIG="stm32f429-discovery"
> BR2_PACKAGE_HOST_UBOOT_TOOLS=y
> 
> Moreover, there are some other issues with elf2flt when the toolchain is built
> (one of the first target binary which get compiled after uClibc is getconf, part of uClibc I guess),
> I am writing another email for that :)

Ok, thanks!

To tell the truth, ARM noMMU support in Buildroot is very much a work
in progress. We have had only some initial Cortex-M3 patches, and a lot
of work remain to be done to make it really usable. Your
patches/reports are definitely welcome!

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com