[3/5] 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.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 toolchain/Config.in                      |  9 +++++++++
 toolchain/helpers.mk                     | 11 +++++++++++
 toolchain/toolchain-external/Config.in   | 12 ++++++++++++
 toolchain/toolchain-external/ext-tool.mk | 11 ++++++++++-
 4 files changed, 42 insertions(+), 1 deletion(-)

Hello,

On Sat,  5 Oct 2013 16:16:12 +0200, Thomas Petazzoni wrote:

> +	if test "$(BR2_TOOLCHAIN_EXTERNAL_MUSL)" = "y" ; then \
> +		ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-arm.so.1 ; \

Crap. This should indeed be conditional on the architecture. I'll fix
that in v2 with the other comments that the patches will receive.

Thomas

Thomas Petazzoni <thomas.petazzoni@free-electrons.com> wrote:
>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.
>
>Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
>---
> toolchain/Config.in                      |  9 +++++++++
> toolchain/helpers.mk                     | 11 +++++++++++
> toolchain/toolchain-external/Config.in   | 12 ++++++++++++
> toolchain/toolchain-external/ext-tool.mk | 11 ++++++++++-
> 4 files changed, 42 insertions(+), 1 deletion(-)
>
>diff --git a/toolchain/Config.in b/toolchain/Config.in
>index 17be32a..61eb520 100644
>--- a/toolchain/Config.in
>+++ b/toolchain/Config.in
>@@ -24,6 +24,15 @@ 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
>diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
>index d5443b5..e8d4168 100644
>--- a/toolchain/helpers.mk
>+++ b/toolchain/helpers.mk
>@@ -214,6 +214,17 @@ check_glibc = \
> 	$(call check_glibc_rpc_feature,$${SYSROOT_DIR})
> 
> #
>+# Check that the selected C library is really musl
>+#
>+# $1: sysroot directory
>+check_musl = \
>+	SYSROOT_DIR="$(strip $1)"; \
>+	if test ! -f $${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
> # feature.
>diff --git a/toolchain/toolchain-external/Config.in b/toolchain/toolchain-external/Config.in
>index c53577e..89c799e 100644
>--- a/toolchain/toolchain-external/Config.in
>+++ b/toolchain/toolchain-external/Config.in
>@@ -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
>diff --git a/toolchain/toolchain-external/ext-tool.mk b/toolchain/toolchain-external/ext-tool.mk
>index 8762a46..f642017 100644
>--- a/toolchain/toolchain-external/ext-tool.mk
>+++ b/toolchain/toolchain-external/ext-tool.mk
>@@ -63,6 +63,10 @@ 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
>@@ -369,7 +373,7 @@ $(STAMP_DIR)/ext-toolchain-checked: $(TOOLCHAIN_EXTERNAL_DEPENDENCIES)
> 	@$(call MESSAGE,"Checking external toolchain settings")
> 	$(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 "$${SYSROOT_DIR}" ; then \
> 		@echo "External toolchain doesn't support --sysroot. Cannot use." ; \
> 		exit 1 ; \
>@@ -384,6 +388,8 @@ $(STAMP_DIR)/ext-toolchain-checked: $(TOOLCHAIN_EXTERNAL_DEPENDENCIES)
> 	fi ; \
> 	if test "$(BR2_TOOLCHAIN_EXTERNAL_UCLIBC)" = "y" ; then \
> 		$(call check_uclibc,$${SYSROOT_DIR}) ; \
>+	elif test "$(BR2_TOOLCHAIN_EXTERNAL_MUSL)" = "y" ; then \
>+		$(call check_musl,$${SYSROOT_DIR}) ; \
> 	else \
> 		$(call check_glibc,$${SYSROOT_DIR}) ; \
> 	fi
>@@ -464,6 +470,9 @@ $(STAMP_DIR)/ext-toolchain-installed: $(STAMP_DIR)/ext-toolchain-checked
> 			$(call copy_toolchain_lib_root,$${ARCH_SYSROOT_DIR},$${SUPPORT_LIB_DIR},$${ARCH_LIB_DIR},$$libs,/usr/lib); \
> 		done ; \
> 	fi ; \
>+	if test "$(BR2_TOOLCHAIN_EXTERNAL_MUSL)" = "y" ; then \
>+		ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-arm.so.1 ; \
>+	fi ; \

Is this intentionally arm-specific?

> 	$(call MESSAGE,"Copying external toolchain sysroot to staging...") ; \
> 	$(call copy_toolchain_sysroot,$${SYSROOT_DIR},$${ARCH_SYSROOT_DIR},$${ARCH_SUBDIR},$${ARCH_LIB_DIR},$${SUPPORT_LIB_DIR}) ; \
> 	if test "$(BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY)" = "y"; then \

Thomas Petazzoni <thomas.petazzoni@free-electrons.com> wrote:
>Hello,
>
>On Sat,  5 Oct 2013 16:16:12 +0200, Thomas Petazzoni wrote:
>
>> +	if test "$(BR2_TOOLCHAIN_EXTERNAL_MUSL)" = "y" ; then \
>> +		ln -sf libc.so $(TARGET_DIR)/lib/ld-musl-arm.so.1 ; \
>
>Crap. This should indeed be conditional on the architecture. I'll fix
>that in v2 with the other comments that the patches will receive.

Ah I hadn't seen this yet... please disregard my previous mail...