Commit a1d94aaa authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Peter Korsgaard
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toolchain-external: add support for musl C library 

This commit adds support for external toolchains based on the musl C
library, as available from http://www.musl-libc.org.

Note that the pre-built musl toolchains available from
http://musl.codu.org/ are not working for the moment, since they lack
sysroot support. However, this problem has been reported to the
maintainer, who has already added sysroot support in his scripts at
https://bitbucket.org/GregorR/musl-cross

, and therefore the next
version of the pre-built toolchains should work with Buildroot
out-of-the-box. In the mean time, the musl-cross script must be used
to build the toolchain.

[Peter: reword comment]
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: default avatarPeter Korsgaard <peter@korsgaard.com>
parent 8e05ebca

toolchain/Config.in

+9 −0
Original line number Diff line number Diff line
@@ -15,6 +15,15 @@ config BR2_TOOLCHAIN_USES_GLIBC 
config BR2_TOOLCHAIN_USES_UCLIBC

	bool



config BR2_TOOLCHAIN_USES_MUSL

	bool

	select BR2_LARGEFILE

	select BR2_INET_IPV6

	select BR2_USE_WCHAR

	select BR2_ENABLE_LOCALE

	select BR2_TOOLCHAIN_HAS_THREADS

	select BR2_TOOLCHAIN_HAS_THREADS_DEBUG



choice

	prompt "Toolchain type"

	help

toolchain/helpers.mk

+11 −0
Original line number Diff line number Diff line
@@ -208,6 +208,17 @@ check_glibc = \ 
	$(call check_glibc_feature,BR2_USE_MMU,MMU support) ;\

	$(call check_glibc_rpc_feature,$${SYSROOT_DIR})



#

# Check that the selected C library really is musl

#

# $1: sysroot directory

check_musl = \

	SYSROOT_DIR="$(strip $1)"; \

	if test ! -f $${SYSROOT_DIR}/lib/libc.so -o -e $${SYSROOT_DIR}/lib/libm.so ; then \

		echo "Incorrect selection of the C library" ; \

		exit -1; \

	fi



#

# Check the conformity of Buildroot configuration with regard to the

# uClibc configuration of the external toolchain, for a particular

toolchain/toolchain-external/Config.in

+12 −0
Original line number Diff line number Diff line
@@ -860,6 +860,10 @@ config BR2_TOOLCHAIN_EXTERNAL_UCLIBC 
	bool

	select BR2_TOOLCHAIN_USES_UCLIBC



config BR2_TOOLCHAIN_EXTERNAL_MUSL

	bool

	select BR2_TOOLCHAIN_USES_MUSL



if BR2_TOOLCHAIN_EXTERNAL_CUSTOM



choice
@@ -882,6 +886,13 @@ config BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC 
	  eglibc configured to exclude key features may cause build failures to

	  some packages.



config BR2_TOOLCHAIN_EXTERNAL_CUSTOM_MUSL

	bool "musl"

	select BR2_TOOLCHAIN_EXTERNAL_MUSL

	help

	  Select this option if your external toolchain uses the

	  'musl' C library, available from http://www.musl-libc.org/.



endchoice



if BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC
@@ -952,6 +963,7 @@ endif # BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC 
config BR2_TOOLCHAIN_EXTERNAL_INET_RPC

	bool "Toolchain has RPC support?"

	select BR2_TOOLCHAIN_HAS_NATIVE_RPC

	depends on !BR2_TOOLCHAIN_EXTERNAL_MUSL

	default y if BR2_TOOLCHAIN_EXTERNAL_GLIBC

	help

	  Select this option if your external toolchain supports

toolchain/toolchain-external/toolchain-external.mk

+17 −1
Original line number Diff line number Diff line
@@ -68,6 +68,10 @@ ifeq ($(BR2_TOOLCHAIN_EXTERNAL_GLIBC),y) 
LIB_EXTERNAL_LIBS+=libnss_files.so.* libnss_dns.so.*

endif



ifeq ($(BR2_TOOLCHAIN_EXTERNAL_MUSL),y)

LIB_EXTERNAL_LIBS += libc.so libgcc_s.so.*

endif



ifeq ($(BR2_INSTALL_LIBSTDCPP),y)

USR_LIB_EXTERNAL_LIBS+=libstdc++.so.*

endif
@@ -353,7 +357,7 @@ endif 
define TOOLCHAIN_EXTERNAL_CONFIGURE_CMDS

	$(Q)$(call check_cross_compiler_exists,$(TOOLCHAIN_EXTERNAL_CC))

	$(Q)LIBC_A_LOCATION=`readlink -f $$(LANG=C $(TOOLCHAIN_EXTERNAL_CC) -print-file-name=libc.a)` ; \

	SYSROOT_DIR=`echo $${LIBC_A_LOCATION} | sed -r -e 's:usr/lib(32|64)?/(.*/)?libc\.a::'` ; \

	SYSROOT_DIR=`echo $${LIBC_A_LOCATION} | sed -r -e 's:(usr/)?lib(32|64)?/(.*/)?libc\.a::'` ; \

	if test -z "$${SYSROOT_DIR}" ; then \

		@echo "External toolchain doesn't support --sysroot. Cannot use." ; \

		exit 1 ; \
@@ -368,11 +372,23 @@ define TOOLCHAIN_EXTERNAL_CONFIGURE_CMDS 
	fi ; \

	if test "$(BR2_TOOLCHAIN_EXTERNAL_UCLIBC)" = "y" ; then \

		$(call check_uclibc,$${SYSROOT_DIR}) ; \

	elif test "$(BR2_TOOLCHAIN_EXTERNAL_MUSL)" = "y" ; then \

		$(call check_musl,$${SYSROOT_DIR}) ; \

	else \

		$(call check_glibc,$${SYSROOT_DIR}) ; \

	fi

endef



# With the musl C library, the libc.so library directly plays the role

# 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)

define TOOLCHAIN_EXTERNAL_MUSL_LD_LINK

	ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-$(ARCH).so.1

endef

TOOLCHAIN_EXTERNAL_POST_INSTALL_STAGING_HOOKS += TOOLCHAIN_EXTERNAL_MUSL_LD_LINK

endif



# Integration of the toolchain into Buildroot: find the main sysroot

# and the variant-specific sysroot, then copy the needed libraries to

# the $(TARGET_DIR) and copy the whole sysroot (libraries and headers)