uclibc-ng & ARC developers: I'm trying to use buildroot to build the latest ARC toolchain (arc-2016.09-eng007) against our vendor-provided 2.6.35.12 ARC Linux kernel. (Yes, it is an ancient kernel, but that's what I have to work with for now, unfortunately.) The buildroot config is: BR2_arcle=y BR2_arc750d=y BR2_ENABLE_DEBUG=y BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_REALLY_OLD=y BR2_TOOLCHAIN_BUILDROOT_INET_RPC=y BR2_TOOLCHAIN_BUILDROOT_WCHAR=y BR2_TOOLCHAIN_BUILDROOT_LOCALE=y BR2_PTHREAD_DEBUG=y BR2_TOOLCHAIN_BUILDROOT_USE_SSP=y BR2_TOOLCHAIN_BUILDROOT_CXX=y BR2_LINUX_KERNEL=y BR2_LINUX_KERNEL_CUSTOM_LOCAL=y BR2_LINUX_KERNEL_CUSTOM_LOCAL_PATH="/path/to/vendor/2.6.35.12/kernel" BR2_LINUX_KERNEL_VERSION="2.6.35.12" With this setup, I'm running into various uclibc-ng 1.0.17 build errors: 1) ./include/sys/procfs.h:30:28: error: invalid application of 'sizeof' to incomplete type 'struct user_regs_struct' #define ELF_NGREG (sizeof (struct user_regs_struct) / sizeof(elf_greg_t)) QUICK FIX: Copied 'struct user_regs_struct' definition from corresponding 2.6.35.12 kernel header to libc/sysdeps/linux/arc/sys/user.h 2) ./include/sys/cachectl.h:13:26: fatal error: asm/cachectl.h: No such file or directory #include <asm/cachectl.h> QUICK FIX: Commented the above line out in libc/sysdeps/linux/arc/sys/cachectl.h 3) In file included from .../buildroot/output/build/linux-headers-custom/usr/include/linux/posix_types.h:47:0, from .../buildroot/output/build/linux-headers-custom/usr/include/linux/types.h:8, from .../buildroot/output/build/linux-headers-custom/usr/include/linux/rtnetlink.h:4, from libc/inet/netlinkaccess.h:26, from libc/inet/ifaddrs.c:36: .../buildroot/output/build/linux-headers-custom/usr/include/asm/posix_types.h:22:25: error: conflicting types for '__kernel_mode_t' typedef unsigned short __kernel_mode_t; ^ In file included from ./include/bits/types.h:30:0, from ./include/sys/types.h:30, from ./include/sys/uio.h:23, from ./include/sys/socket.h:27, from ./include/ifaddrs.h:23, from libc/inet/ifaddrs.c:22: ./include/bits/kernel_types.h:25:23: note: previous declaration of '__kernel_mode_t' was here typedef unsigned int __kernel_mode_t; ^ QUICK FIX: Added #include <asm/posix_types.h> on top of libc/sysdeps/linux/arc/bits/kernel_types.h and wrapped the uclibc definitions with #ifndef _ASM_ARC_POSIX_TYPES_H ... #define _ASM_ARC_POSIX_TYPES_H ... #endif to match the kernel header wrappers. Also, needed to add #ifndef ... #define ... #endif wraps to __FD_* definitions in libc/sysdeps/linux/common/bits/select.h 4) /usr/bin/make -j1 -C .../buildroot/output/build/uclibc-1.0.17 CC=".../buildroot/output/host/usr/bin/arc-buildroot-linux-uclibc-gcc" CPP=".../buildroot/output/host/usr/bin/arc-buildroot-linux-uclibc-cpp" LD=".../buildroot/output/host/usr/bin/arc-buildroot-linux-uclibc-ld" ARCH="arc" PREFIX=.../buildroot/output/target utils install_utils make[3]: Nothing to be done for `locale_headers'. CC utils/getconf ../lib/libc.so.1: undefined reference to `__xstat32_conv' ../lib/libc.so.1: undefined reference to `__xstat64_conv' collect2: error: ld returned 1 exit status make[3]: *** [../utils/getconf] Error 1 make[2]: *** [utils] Error 2 make[1]: *** [/usr/local/google/home/pgynther/clients/buildroot/output/build/uclibc-1.0.17/.stamp_target_installed] Error 2 make: *** [_all] Error 2 QUICK FIX: Created libc/sysdeps/linux/arc/bits/kernel_stat.h file from corresponding kernel definitions and also added 'select ARCH_HAS_DEPRECATED_SYSCALLS' in extra/Configs/Config.arc After the above 4 patches have been applied, buildroot is able to build the toolchain successfully. And then, using this new toolchain, I'm able to build our internal 2.6.35.12 kernel + initramfs image. However: Once I boot the newly built image, the kernel boots fine, but /init (busybox) crashes every time. And same happens with /bin/sh (dash). Basically, no userland binary built with this toolchain runs on top of 2.6.35.12 kernel. No matter what I provide on kernel command line parameter "rdinit=/path/to/binary", the boot always ends with "Attempted to kill init!" because the kernel doesn't like the userland binaries. [ 2.070000] TCP cubic registered [ 2.075000] NET: Registered protocol family 10 [ 2.080000] NET: Registered protocol family 17 [ 2.085000] 802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com> [ 2.090000] All bugs added by David S. Miller <davem@redhat.com> [ 2.100000] Freeing unused kernel memory: 19904k freed [84938000] TO [85ca8000] [ 2.105000] Common mmap addr-space starts 2c0f0000 [ 2.115000] Kernel panic - not syncing: Attempted to kill init! Questions: 1) Does the latest ARC toolchain use some new ABI for binaries that makes them incompatible with 2.6.35.12 kernel? 2) Is uclibc-ng 1.0.17 supposed to be compatible with 2.6.x kernel headers? Any help is greatly appreciated. Thanks. -- Petri