system: update lib64/32 symlink creation for mips64n32 and gcc >= 5.1.0

From: Thomas De Schampheleire <[email protected]>

In gcc 5.1.0, a change was introduced which causes internal search paths inside the sysroot to be relative to 'lib64' rather than 'lib'. See [1] [2] and [3].

For example for dtc:

     LD convert-dtsv0
    /opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/../../../../mips64-octeon-linux-gnu/bin/ld: cannot find crt1.o: No such file or directory
    /opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/../../../../mips64-octeon-linux-gnu/bin/ld: cannot find crti.o: No such file or directory
    collect2: error: ld returned 1 exit status
    make[1]: *** [Makefile:236: convert-dtsv0] Error 1
    make[1]: *** Waiting for unfinished jobs....
    make[1]: Leaving directory '/opt/buildroot/output/build/dtc-1.4.7'
    make: *** [package/pkg-generic.mk:241: /opt/buildroot/output/build/dtc-1.4.7/.stamp_built] Error 2

In this case, crt1.o was searched for in following locations:

    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/n32/octeon3/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/n32/octeon3/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/../../../../mips64-octeon-linux-gnu/lib/mips64-octeon-linux-gnu/7.3.0/n32/octeon3/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/../../../../mips64-octeon-linux-gnu/lib/../lib32-fp/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/lib64/mips64-octeon-linux-gnu/7.3.0/n32/octeon3/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/lib64/../lib32-fp/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/usr/lib64/mips64-octeon-linux-gnu/7.3.0/n32/octeon3/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/usr/lib64/../lib32-fp/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/../../../../mips64-octeon-linux-gnu/lib/mips64-octeon-linux-gnu/7.3.0/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/opt/ext-toolchain/bin/../lib/gcc/mips64-octeon-linux-gnu/7.3.0/../../../../mips64-octeon-linux-gnu/lib/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/lib64/mips64-octeon-linux-gnu/7.3.0/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/lib64/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/usr/lib64/mips64-octeon-linux-gnu/7.3.0/crt1.o", R_OK) = -1 ENOENT (No such file or directory)
    16073 access("/opt/buildroot/output/host/mips64-buildroot-linux-gnu/sysroot/usr/lib64/crt1.o", R_OK) = -1 ENOENT (No such file or directory)

As can be seen above, all attempted paths contain 'lib64' as base, instead of 'lib' or 'lib32', e.g.

.../sysroot/lib64/../lib32-fp/crt1.o
.../sysroot/lib64/crt1.o

This problem was detected on a gcc 7.x toolchain provided by Marvell as part of their Octeon SDK. For this toolchain, here are the values of the paths as detected by the Buildroot toolchain logic, for two different Octeon processors:

- octeon2 (soft-float) (-mabi=n32 -march=octeon2):
SYSROOT_DIR=/opt/buildroot/output/host/opt/ext-toolchain/mips64-octeon-linux-gnu/sys-root/; ARCH_SYSROOT_DIR=/opt/buildroot/output/host/opt/ext-toolchain/mips64-octeon-linux-gnu/sys-root/; ARCH_SUBDIR=;
ARCH_LIB_DIR=lib32/octeon2; SUPPORT_LIB_DIR=/opt/buildroot/output/host/opt/ext-toolchain/mips64-octeon-linux-gnu/lib32/octeon2/

- octeon3 (hard-float) (-mabi=n32 -march=octeon3):
SYSROOT_DIR=/opt/buildroot/output/host/opt/ext-toolchain/mips64-octeon-linux-gnu/sys-root/; ARCH_SYSROOT_DIR=/opt/buildroot/output/host/opt/ext-toolchain/mips64-octeon-linux-gnu/sys-root/; ARCH_SUBDIR=;
ARCH_LIB_DIR=lib32-fp; SUPPORT_LIB_DIR=/opt/buildroot/output/host/opt/ext-toolchain/mips64-octeon-linux-gnu/lib32-fp/

For both cases (MIPS64n32) Buildroot created a symlink 'lib32->lib', from SYSTEM_LIB_SYMLINK in system/system.mk. Additionally, the function create_lib_symlinks in toolchain/toolchain-external/pkg-toolchain-external.mk will use ARCH_LIB_DIR and create an additional link $(ARCH_LIB_DIR)->lib.
For the Octeon3 case this thus results in the following symlinks (where the 'lib32' one is normally not needed):

    lib32 -> lib/
    lib32-fp -> lib/

Since the toolchain is searching based on a 'lib64' component, it will fail to find its internal paths.

To solve the problem, we need to create an additional symlink 'lib64':

    lib64 -> lib/

[1] https://github.com/gcc-mirror/gcc/commit/257ccd463a4f25495b252a3bdf989d057c54678d
[2] https://gcc.gnu.org/ml/gcc-patches/2014-10/msg03377.html
[3] https://gcc.gnu.org/ml/gcc-patches/2014-11/msg00539.html

---
 system/system.mk | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

v2:
- Extend commit msg with more details (ThomasP)

index 8db87cb129..8fe2c138b0 100644
@@ -56,9 +56,18 @@ define SYSTEM_RSYNC
 endef
 
 # Make a symlink lib32->lib or lib64->lib as appropriate.
-# MIPS64/n32 requires lib32 even though it's a 64-bit arch.
+# MIPS64/n32 requires lib32 even though it's a 64-bit arch. However, since gcc
+# 5.1.0 internal compiler paths in sysroot are relative to lib64, so we must
+# create both.
 # $(1): base dir (either staging or target)
-ifeq ($(BR2_ARCH_IS_64)$(BR2_MIPS_NABI32),y)
+ifeq ($(BR2_MIPS_NABI32),y)
+define SYSTEM_LIB_SYMLINK
+	ln -snf lib $(1)/lib64
+	ln -snf lib $(1)/usr/lib64
+	ln -snf lib $(1)/lib32
+	ln -snf lib $(1)/usr/lib32
+endef
+else ifeq ($(BR2_ARCH_IS_64),y)
 define SYSTEM_LIB_SYMLINK
 	ln -snf lib $(1)/lib64
 	ln -snf lib $(1)/usr/lib64

2.24.1

Applied to master, thanks.

Thomas

Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com