picolibc: Add configuration to select picolibc as the system libc

This moves the picolibc configuration values under C-library -> picolibc
so that they will be more easily discovered.

Signed-off-by: Joakim Nohlgård <joakim@nohlgard.se>

4 files changed, 251 insertions, 183 deletions

diff --git a/config/comp_libs/picolibc.in b/config/comp_libs/picolibc.in
index 99f0e452..4b283aec 100644
--- a/config/comp_libs/picolibc.in
+++ b/config/comp_libs/picolibc.in
@@ -1,6 +1,9 @@
-# picolibc options
+# picolibc companion library options
 
+## no-package
 ## depends on BARE_METAL && CONFIGURE_has_meson && CONFIGURE_has_ninja
+## depends on !LIBC_PICOLIBC
+## select LIBC_PICOLIBC_SHOW
 
 ## help This option adds Picolibc to an existing configuration which may have
 ## help a C library, allowing you to install both and select between them
@@ -9,124 +12,21 @@
 ## help Picolibc is a C library intended for use on embedded systems. It is a
 ## help conglomeration of several library parts, all under BSD-compatible software
 ## help licenses that make them easily usable on embedded products.
+## help
+## help Configuration for picolibc can be found under:
+## help -> C-library
+## help   -> picolibc
 
 config LIBC_PICOLIBC_GCC_LIBSTDCXX
     bool
-    prompt "Compile libstdc++ picolibc variant"
+    prompt "Compile companion libstdc++ picolibc variant"
     default y
     depends on CC_LANG_CXX
     help
       This option compiles an additional target libstdc++ for use with
-      picolibc. This version is linked when "--specs=picolibcpp.specs"
-      is specified.
+      the picolibc companion library. This version is linked when
+      "--specs=picolibcpp.specs" is specified.
 
-config LIBC_PICOLIBC_CXA_ATEXIT
-    def_bool y
-    select LIBC_PROVIDES_CXA_ATEXIT
-
-config LIBC_PICOLIBC_TARGET_CFLAGS
-    string
-    prompt "Target CFLAGS for picolibc"
-    default ""
-    help
-      Used to add specific options when compiling the target libraries
-      (eg. -ffunction-sections -fdata-sections), which can't be defined
-      in global TARGET_CFLAGS, because they shall be not used for the
-      gcc target libraries.
-      Note:  Both TARGET_CFLAGS and LIBC_PICOLIBC_TARGET_CFLAGS are used
-             to compile the libraries.
-
-      Leave blank if you don't know better.
-
-config LIBC_PICOLIBC_IO_C99FMT
-    bool
-    prompt "Enable IOs on C99 formats"
-    default y
-    help
-      Enable support for IOs on C99 formats.
-
-config LIBC_PICOLIBC_REGISTER_FINI
-    bool
-    prompt "Enable finalization function registration using atexit"
-    help
-        Enable finalization function registration using atexit.
-
-config LIBC_PICOLIBC_ATEXIT_DYNAMIC_ALLOC
-    bool
-    prompt "Enable dynamic allocation of atexit entries"
-    help
-        Enable dynamic allocation of atexit entries.
-
-config LIBC_PICOLIBC_GLOBAL_ATEXIT
-    bool
-    prompt "Enable atexit data structure as global variable"
-    help
-        Enable atexit data structure as global variable, instead
-        of being thread-local.
-
-config LIBC_PICOLIBC_LITE_EXIT
-    bool
-    prompt "Enable lite exit"
-    default y
-    help
-        Enable lite exit, a size-reduced implementation of exit that doesn't
-        invoke clean-up functions such as _fini or global destructors.
-
-config LIBC_PICOLIBC_MULTITHREAD
-    bool
-    prompt "Enable support for multiple threads"
-    default y
-    help
-        Enable support for multiple threads.
-
-config LIBC_PICOLIBC_RETARGETABLE_LOCKING
-    bool
-    prompt "Enable retargetable locking"
-    default y
-    help
-        Enable retargetable locking to allow the operating system to override
-        the dummy lock functions defined within picolibc.
-
-config LIBC_PICOLIBC_EXTRA_SECTIONS
-    bool
-    prompt "Place each function & data element in their own section"
-    help
-        Place each function & data symbol in their own section. This allows
-        the linker to garbage collect unused symbols at link time.
-
-config LIBC_PICOLIBC_ENABLE_TARGET_OPTSPACE
-    bool
-    prompt "Optimize picolibc for size"
-    default y
-    help
-      Pass --enable-target-optspace to picolibc configure.
-
-      This will compile picolibc with -Os.
-
-config LIBC_PICOLIBC_LTO
-    bool
-    prompt "Enable Link Time Optimization"
-    depends on CC_GCC_USE_LTO
-    help
-      Builds the libraries with -flto to enable more aggressive link time
-      optimization. You will need to add -flto-partition=one to your
-      application's link line to keep the RETURN assembler macro together
-      with it's consumers.
-
-config LIBC_PICOLIBC_NANO_MALLOC
-    bool
-    prompt "Enable Nano Malloc"
-    default y
-    help
-      PICOLIBC has two implementations of malloc family's functions, one in
-      `mallocr.c' and the other one in `nano-mallocr.c'.  This options
-      enables the nano-malloc implementation, which is for small systems
-      with very limited memory.  Note that this implementation does not
-      support `--enable-malloc-debugging' any more.
-
-config LIBC_PICOLIBC_EXTRA_CONFIG_ARRAY
-    string
-    prompt "Extra config for picolibc"
-    default ""
-    help
-      Extra flags to pass to meson when configuring picolibc.
+comment "Configuration for picolibc can be found under"
+comment "* -> C-library"
+comment "*   -> picolibc"
diff --git a/config/libc/picolibc.in b/config/libc/picolibc.in
new file mode 100644
index 00000000..cd6da1ed
--- /dev/null
+++ b/config/libc/picolibc.in
@@ -0,0 +1,125 @@
+# picolibc options
+
+## depends on BARE_METAL && CONFIGURE_has_meson && CONFIGURE_has_ninja
+## select CC_CORE_NEEDED
+## select LIBC_SUPPORT_THREADS_NATIVE
+
+## help Picolibc is a C library intended for use on embedded systems. It is a
+## help conglomeration of several library parts, all under BSD-compatible software
+## help licenses that make them easily usable on embedded products.
+## help
+## help This requres GCC with picolibc support which is only available
+## help for GCC version 12.2.0 or later. A crosstool-ng dependency conflict
+## help prevents that from being managed automatically.
+##
+
+config LIBC_PICOLIBC_CXA_ATEXIT
+    def_bool y
+    select LIBC_PROVIDES_CXA_ATEXIT
+
+config LIBC_PICOLIBC_TARGET_CFLAGS
+    string
+    prompt "Target CFLAGS for picolibc"
+    default ""
+    help
+      Used to add specific options when compiling the target libraries
+      (eg. -ffunction-sections -fdata-sections), which can't be defined
+      in global TARGET_CFLAGS, because they shall be not used for the
+      gcc target libraries.
+      Note:  Both TARGET_CFLAGS and LIBC_PICOLIBC_TARGET_CFLAGS are used
+             to compile the libraries.
+
+      Leave blank if you don't know better.
+
+config LIBC_PICOLIBC_IO_C99FMT
+    bool
+    prompt "Enable IOs on C99 formats"
+    default y
+    help
+      Enable support for IOs on C99 formats.
+
+config LIBC_PICOLIBC_REGISTER_FINI
+    bool
+    prompt "Enable finalization function registration using atexit"
+    help
+        Enable finalization function registration using atexit.
+
+config LIBC_PICOLIBC_ATEXIT_DYNAMIC_ALLOC
+    bool
+    prompt "Enable dynamic allocation of atexit entries"
+    help
+        Enable dynamic allocation of atexit entries.
+
+config LIBC_PICOLIBC_GLOBAL_ATEXIT
+    bool
+    prompt "Enable atexit data structure as global variable"
+    help
+        Enable atexit data structure as global variable, instead
+        of being thread-local.
+
+config LIBC_PICOLIBC_LITE_EXIT
+    bool
+    prompt "Enable lite exit"
+    default y
+    help
+        Enable lite exit, a size-reduced implementation of exit that doesn't
+        invoke clean-up functions such as _fini or global destructors.
+
+config LIBC_PICOLIBC_MULTITHREAD
+    bool
+    prompt "Enable support for multiple threads"
+    default y
+    help
+        Enable support for multiple threads.
+
+config LIBC_PICOLIBC_RETARGETABLE_LOCKING
+    bool
+    prompt "Enable retargetable locking"
+    default y
+    help
+        Enable retargetable locking to allow the operating system to override
+        the dummy lock functions defined within picolibc.
+
+config LIBC_PICOLIBC_EXTRA_SECTIONS
+    bool
+    prompt "Place each function & data element in their own section"
+    help
+        Place each function & data symbol in their own section. This allows
+        the linker to garbage collect unused symbols at link time.
+
+config LIBC_PICOLIBC_ENABLE_TARGET_OPTSPACE
+    bool
+    prompt "Optimize picolibc for size"
+    default y
+    help
+      Pass --enable-target-optspace to picolibc configure.
+
+      This will compile picolibc with -Os.
+
+config LIBC_PICOLIBC_LTO
+    bool
+    prompt "Enable Link Time Optimization"
+    depends on CC_GCC_USE_LTO
+    help
+      Builds the libraries with -flto to enable more aggressive link time
+      optimization. You will need to add -flto-partition=one to your
+      application's link line to keep the RETURN assembler macro together
+      with it's consumers.
+
+config LIBC_PICOLIBC_NANO_MALLOC
+    bool
+    prompt "Enable Nano Malloc"
+    default y
+    help
+      PICOLIBC has two implementations of malloc family's functions, one in
+      `mallocr.c' and the other one in `nano-mallocr.c'.  This options
+      enables the nano-malloc implementation, which is for small systems
+      with very limited memory.  Note that this implementation does not
+      support `--enable-malloc-debugging' any more.
+
+config LIBC_PICOLIBC_EXTRA_CONFIG_ARRAY
+    string
+    prompt "Extra config for picolibc"
+    default ""
+    help
+      Extra flags to pass to meson when configuring picolibc.
diff --git a/scripts/build/companion_libs/340-picolibc.sh b/scripts/build/companion_libs/340-picolibc.sh
index 1b005e0b..7b29a820 100644
--- a/scripts/build/companion_libs/340-picolibc.sh
+++ b/scripts/build/companion_libs/340-picolibc.sh
@@ -11,71 +11,13 @@ do_picolibc_for_build() { :; }
 do_picolibc_for_host() { :; }
 do_picolibc_for_target() { :; }
 
-if [ "${CT_COMP_LIBS_PICOLIBC}" = "y" ]; then
-
-# Download picolibc
-do_picolibc_get() {
-    CT_Fetch PICOLIBC
-}
-
-do_picolibc_extract() {
-    CT_ExtractPatch PICOLIBC
-}
-
-#------------------------------------------------------------------------------
-# Build an additional target libstdc++ with "-Os" (optimise for speed) option
-# flag for libstdc++ "picolibc" variant.
-do_cc_libstdcxx_picolibc()
-{
-    local -a final_opts
-    local final_backend
+if [ "${CT_LIBC_PICOLIBC}" = "y" -o "${CT_COMP_LIBS_PICOLIBC}" = "y" ]; then
 
-    if [ "${CT_LIBC_PICOLIBC_GCC_LIBSTDCXX}" = "y" ]; then
-        final_opts+=( "host=${CT_HOST}" )
-        final_opts+=( "libstdcxx_name=picolibc" )
-        final_opts+=( "prefix=${CT_PREFIX_DIR}" )
-        final_opts+=( "complibs=${CT_HOST_COMPLIBS_DIR}" )
-        final_opts+=( "cflags=${CT_CFLAGS_FOR_HOST}" )
-        final_opts+=( "ldflags=${CT_LDFLAGS_FOR_HOST}" )
-        final_opts+=( "lang_list=c,c++" )
-        final_opts+=( "build_step=libstdcxx" )
-        final_opts+=( "extra_config+=('--enable-stdio=stdio_pure')" )
-        final_opts+=( "extra_config+=('--disable-wchar_t')" )
-        if [ "${CT_LIBC_PICOLIBC_ENABLE_TARGET_OPTSPACE}" = "y" ]; then
-            final_opts+=( "enable_optspace=yes" )
-        fi
-
-        if [ "${CT_BARE_METAL}" = "y" ]; then
-            final_opts+=( "mode=baremetal" )
-            final_opts+=( "build_libgcc=yes" )
-            final_opts+=( "build_libstdcxx=yes" )
-            final_opts+=( "build_libgfortran=yes" )
-            if [ "${CT_STATIC_TOOLCHAIN}" = "y" ]; then
-                final_opts+=( "build_staticlinked=yes" )
-            fi
-            final_backend=do_gcc_core_backend
-        else
-            final_backend=do_gcc_backend
-        fi
-
-        CT_DoStep INFO "Installing libstdc++ picolibc"
-        CT_mkdir_pushd "${CT_BUILD_DIR}/build-cc-libstdcxx-picolibc"
-        "${final_backend}" "${final_opts[@]}"
-        CT_Popd
-
-        CT_EndStep
-    fi
-}
-
-do_picolibc_for_target() {
+do_picolibc_common_install() {
     local -a picolibc_opts
     local cflags_for_target
 
-    CT_DoStep INFO "Installing Picolibc library"
-
-    CT_mkdir_pushd "${CT_BUILD_DIR}/build-picolibc-build-${CT_BUILD}"
-
-    CT_DoLog EXTRA "Configuring Picolibc library"
+    CT_DoLog EXTRA "Configuring C library"
 
     # Multilib is the default, so if it is not enabled, disable it.
     if [ "${CT_MULTILIB}" != "y" ]; then
@@ -106,9 +48,6 @@ RETARGETABLE_LOCKING:newlib-retargetable-locking
         fi
     done
 
-    [ "${CT_USE_SYSROOT}" = "y" ] && \
-        picolibc_opts+=( "-Dsysroot-install=true" )
-
     [ "${CT_LIBC_PICOLIBC_EXTRA_SECTIONS}" = "y" ] && \
         CT_LIBC_PICOLIBC_TARGET_CFLAGS="${CT_LIBC_PICOLIBC_TARGET_CFLAGS} -ffunction-sections -fdata-sections"
 
@@ -145,13 +84,24 @@ needs_exe_wrapper = true
 skip_sanity_check = true
 EOF
 
+    local picolibc_sysroot_dir
+    local picolibc_lib_dir
+    if [ "${CT_LIBC_PICOLIBC}" = 'y' ]; then
+        picolibc_sysroot_dir="${CT_SYSROOT_DIR}"
+        picolibc_lib_dir="${CT_SYSROOT_DIR}/lib"
+        picolibc_opts+=( '-Dsystem-libc=true' )
+    else
+        picolibc_sysroot_dir="${CT_PREFIX_DIR}/picolibc"
+        picolibc_lib_dir="${picolibc_sysroot_dir}/${CT_TARGET}/lib"
+    fi
+
     CT_DoExecLog CFG                                               \
     meson                                                          \
         --cross-file picolibc-cross.txt                            \
-        --prefix="${CT_PREFIX_DIR}"                                \
-        -Dincludedir=picolibc/include                              \
-        -Dlibdir=picolibc/${CT_TARGET}/lib                         \
-        -Dspecsdir="${CT_SYSROOT_DIR}"/lib                         \
+        --prefix="${picolibc_sysroot_dir}"                         \
+        -Dincludedir=include                                       \
+        -Dlibdir="${picolibc_lib_dir}"                             \
+        -Dspecsdir="${CT_SYSROOT_DIR}/lib"                         \
         "${CT_SRC_DIR}/picolibc"                                   \
         "${picolibc_opts[@]}"                                      \
         "${CT_LIBC_PICOLIBC_EXTRA_CONFIG_ARRAY[@]}"
@@ -161,11 +111,75 @@ EOF
 
     CT_DoLog EXTRA "Installing C library"
     CT_DoExecLog ALL ninja install
+}
+
+fi # CT_LIBC_PICOLIBC -o CT_COMP_LIBS_PICOLIBC
+
+if [ "${CT_COMP_LIBS_PICOLIBC}" = "y" ]; then
+
+do_cc_libstdcxx_picolibc() { :; }
+
+# Download picolibc
+do_picolibc_get() {
+    CT_Fetch PICOLIBC
+}
+
+do_picolibc_extract() {
+    CT_ExtractPatch PICOLIBC
+}
+
+if [ "${CT_LIBC_PICOLIBC_GCC_LIBSTDCXX}" = "y" ]; then
+#------------------------------------------------------------------------------
+# Build an additional target libstdc++ with "-Os" (optimise for speed) option
+# flag for libstdc++ "picolibc" variant.
+do_cc_libstdcxx_picolibc()
+{
+    local -a final_opts
+    local final_backend
 
+    final_opts+=( "host=${CT_HOST}" )
+    final_opts+=( "libstdcxx_name=picolibc" )
+    final_opts+=( "prefix=${CT_PREFIX_DIR}" )
+    final_opts+=( "complibs=${CT_HOST_COMPLIBS_DIR}" )
+    final_opts+=( "cflags=${CT_CFLAGS_FOR_HOST}" )
+    final_opts+=( "ldflags=${CT_LDFLAGS_FOR_HOST}" )
+    final_opts+=( "lang_list=c,c++" )
+    final_opts+=( "build_step=libstdcxx" )
+    final_opts+=( "extra_config+=('--enable-stdio=stdio_pure')" )
+    final_opts+=( "extra_config+=('--disable-wchar_t')" )
+    if [ "${CT_LIBC_PICOLIBC_ENABLE_TARGET_OPTSPACE}" = "y" ]; then
+        final_opts+=( "enable_optspace=yes" )
+    fi
+
+    if [ "${CT_BARE_METAL}" = "y" ]; then
+        final_opts+=( "mode=baremetal" )
+        final_opts+=( "build_libgcc=yes" )
+        final_opts+=( "build_libstdcxx=yes" )
+        final_opts+=( "build_libgfortran=yes" )
+        if [ "${CT_STATIC_TOOLCHAIN}" = "y" ]; then
+            final_opts+=( "build_staticlinked=yes" )
+        fi
+        final_backend=do_gcc_core_backend
+    else
+        final_backend=do_gcc_backend
+    fi
+
+    CT_DoStep INFO "Installing libstdc++ picolibc"
+    CT_mkdir_pushd "${CT_BUILD_DIR}/build-cc-libstdcxx-picolibc"
+    "${final_backend}" "${final_opts[@]}"
     CT_Popd
+
     CT_EndStep
+}
+fi # CT_LIBC_PICOLIBC_GCC_LIBSTDCXX
 
+do_picolibc_for_target() {
+    CT_DoStep INFO "Installing Picolibc library"
+    CT_mkdir_pushd "${CT_BUILD_DIR}/build-picolibc-build-${CT_BUILD}"
+    do_picolibc_common_install
+    CT_Popd
+    CT_EndStep
     do_cc_libstdcxx_picolibc
 }
 
-fi
+fi # CT_COMP_LIBS_PICOLIBC
diff --git a/scripts/build/libc/picolibc.sh b/scripts/build/libc/picolibc.sh
new file mode 100644
index 00000000..7e71c29b
--- /dev/null
+++ b/scripts/build/libc/picolibc.sh
@@ -0,0 +1,29 @@
+# This file adds functions to use the Picolibc library as the system libc
+# Copyright © 2022 Joakim Nohlgård
+# Licensed under the GPL v2 or later. See COPYING in the root of this package
+
+picolibc_get()
+{
+    CT_Fetch PICOLIBC
+}
+
+picolibc_extract()
+{
+    CT_ExtractPatch PICOLIBC
+}
+
+picolibc_headers()
+{
+    CT_DoStep INFO "Installing C library headers"
+    CT_DoExecLog ALL cp -a "${CT_SRC_DIR}/picolibc/newlib/libc/include/." "${CT_HEADERS_DIR}"
+    CT_EndStep
+}
+
+picolibc_main()
+{
+    CT_DoStep INFO "Installing C library"
+    CT_mkdir_pushd "${CT_BUILD_DIR}/build-libc"
+    do_picolibc_common_install
+    CT_Popd
+    CT_EndStep
+}