[Buildroot] [PATCH] toolchain-external: adjust logic for musl dynamic linker symlink

[Buildroot] [PATCH] toolchain-external: adjust logic for musl dynamic linker symlink

[Thomas Petazzoni]

This commit changes the strategy to know what symlink should be
created for the musl dynamic linker. For now, we have in Buildroot the
logic to decide what the symlink name should be. However, despite
numerous fixes, there are still some cases that are missing, such as
mips64el-n32, where the symlink is ld-musl-mipsn32el.so.1.

So, instead of trying to make Buildroot aware of all the possible
names, simply get it from the external toolchain.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 toolchain/toolchain-external/pkg-toolchain-external.mk | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
index 856be65..83bfc13 100644
--- a/toolchain/toolchain-external/pkg-toolchain-external.mk
+++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
@@ -477,21 +477,10 @@ endef
 # of the dynamic library loader. We just need to create a symbolic
 # link to libc.so with the appropriate name.
 ifeq ($(BR2_TOOLCHAIN_EXTERNAL_MUSL),y)
-ifeq ($(BR2_i386),y)
-MUSL_ARCH = i386
-else ifeq ($(BR2_ARM_EABIHF),y)
-MUSL_ARCH = armhf
-else ifeq ($(BR2_mips):$(BR2_SOFT_FLOAT),y:y)
-MUSL_ARCH = mips-sf
-else ifeq ($(BR2_mipsel):$(BR2_SOFT_FLOAT),y:y)
-MUSL_ARCH = mipsel-sf
-else ifeq ($(BR2_sh),y)
-MUSL_ARCH = sh
-else
-MUSL_ARCH = $(ARCH)
-endif
 define TOOLCHAIN_EXTERNAL_MUSL_LD_LINK
-	ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-$(MUSL_ARCH).so.1
+	SYSROOT_DIR="$(call toolchain_find_sysroot,$(TOOLCHAIN_EXTERNAL_CC))" ; \
+	LD_MUSL_SYMLINK="`basename $${SYSROOT_DIR}/lib/ld-musl*.so*`" ; \
+	ln -sf libc.so $(TARGET_DIR)/lib/$${LD_MUSL_SYMLINK}
 endef
 endif
 
-- 
2.9.4

[Buildroot] [PATCH] toolchain-external: adjust logic for musl dynamic linker symlink

[Yann E. MORIN]

Thomas, All,

On 2017-06-18 22:11 +0200, Thomas Petazzoni spake thusly:
> This commit changes the strategy to know what symlink should be
> created for the musl dynamic linker. For now, we have in Buildroot the
> logic to decide what the symlink name should be. However, despite
> numerous fixes, there are still some cases that are missing, such as
> mips64el-n32, where the symlink is ld-musl-mipsn32el.so.1.
> 
> So, instead of trying to make Buildroot aware of all the possible
> names, simply get it from the external toolchain.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  toolchain/toolchain-external/pkg-toolchain-external.mk | 17 +++--------------
>  1 file changed, 3 insertions(+), 14 deletions(-)
> 
> diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
> index 856be65..83bfc13 100644
> --- a/toolchain/toolchain-external/pkg-toolchain-external.mk
> +++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
> @@ -477,21 +477,10 @@ endef
>  # of the dynamic library loader. We just need to create a symbolic
>  # link to libc.so with the appropriate name.
>  ifeq ($(BR2_TOOLCHAIN_EXTERNAL_MUSL),y)
> -ifeq ($(BR2_i386),y)
> -MUSL_ARCH = i386
> -else ifeq ($(BR2_ARM_EABIHF),y)
> -MUSL_ARCH = armhf
> -else ifeq ($(BR2_mips):$(BR2_SOFT_FLOAT),y:y)
> -MUSL_ARCH = mips-sf
> -else ifeq ($(BR2_mipsel):$(BR2_SOFT_FLOAT),y:y)
> -MUSL_ARCH = mipsel-sf
> -else ifeq ($(BR2_sh),y)
> -MUSL_ARCH = sh
> -else
> -MUSL_ARCH = $(ARCH)
> -endif
>  define TOOLCHAIN_EXTERNAL_MUSL_LD_LINK
> -	ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-$(MUSL_ARCH).so.1
> +	SYSROOT_DIR="$(call toolchain_find_sysroot,$(TOOLCHAIN_EXTERNAL_CC))" ; \
> +	LD_MUSL_SYMLINK="`basename $${SYSROOT_DIR}/lib/ld-musl*.so*`" ; \
> +	ln -sf libc.so $(TARGET_DIR)/lib/$${LD_MUSL_SYMLINK}

I am not too fond of wildcard-matching. Instead, we could probalby build
a simple file and extract the interpreter from the generated bunary;

    $(CROSS)-gcc -o foo -xc - <<<'int main() { return 0; }'
    LD_MUSL_SYMLINK=$$(\
        LC_ALL=C $(CROSS)-readelf -a foo \
        |sed -r -e '/.*Requesting program interpreter: (.+)\]$/!d; s//\1/'
    )
    rm foo

or something along those lines (unfortunately, readelf can't read from
stdin, and wants a real file (not a pipe) as input)...

Regards,
Yann E. MORIN.

>  endef
>  endif
>  
> -- 
> 2.9.4
> 
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

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