musl: Add multilib support.

Signed-off-by: Alexey Neyman <stilor@att.net>

scripts/build/arch.sh

@@ -57,5 +57,12 @@ CT_DoArchUClibcHeaderDir() {
     :;
 }
 
+# Multilib/MUSL: Adjust header installation path for given CFLAGS
+# Usage: CT_DoArchMUSLHeaderDir <path-variable> <cflags>
+CT_DoArchMUSLHeaderDir() {
+    # Only needed if a given architecture may select different MUSL architectures.
+    :;
+}
+
 # Override from the actual arch implementation as needed.
 . "${CT_LIB_DIR}/scripts/build/arch/${CT_ARCH}.sh"

scripts/build/arch/x86.sh

@@ -167,3 +167,14 @@ CT_DoArchUClibcHeaderDir() {
         eval "${dir_var}="$( ${CT_TARGET}-gcc -print-multiarch ${cflags} )
     fi
 }
+
+CT_DoArchMUSLHeaderDir() {
+    local dir_var="${1}"
+    local cflags="${2}"
+
+    # If it is non-default multilib, add a suffix with architecture (reported by gcc)
+    # to the headers installation path.
+    if [ -n "${cflags}" ]; then
+        eval "${dir_var}="$( ${CT_TARGET}-gcc -print-multiarch ${cflags} )
+    fi
+}

scripts/build/libc/musl.sh

@@ -32,44 +32,52 @@ do_libc_post_cc() {
     :
 }
 
-# This backend builds the C library
-# Usage: do_libc_backend param=value [...]
-#   Parameter           : Definition                      : Type      : Default
-#   libc_mode           : 'startfiles' or 'final'         : string    : (none)
 do_libc_backend() {
     local libc_mode
-    local -a extra_cflags
+    local arg
-    local -a extra_config
-    local src_dir="${CT_SRC_DIR}/${CT_LIBC}-${CT_LIBC_VERSION}"
-    local libc_headers libc_startfiles libc_full
-    local multi_os_dir multi_root multilib_dir
 
     for arg in "$@"; do
         eval "${arg// /\\ }"
     done
 
     case "${libc_mode}" in
-        startfiles)
+        startfiles)     CT_DoStep INFO "Installing C library headers & start files";;
-            CT_DoStep INFO "Installing C library headers & start files"
+        final)          CT_DoStep INFO "Installing C library";;
-            libc_headers=y
-            libc_startfiles=y
-            libc_full=
-            ;;
-        final)
-            CT_DoStep INFO "Installing C library"
-            libc_headers=
-            libc_startfiles=
-            libc_full=y
-            ;;
         *)              CT_Abort "Unsupported (or unset) libc_mode='${libc_mode}'";;
     esac
 
-    multi_root=$( "${CT_TARGET}-gcc" -print-sysroot )
+    CT_mkdir_pushd "${CT_BUILD_DIR}/build-libc-${libc_mode}"
-    multi_os_dir=$( "${CT_TARGET}-gcc" -print-multi-os-directory )
+    CT_IterateMultilibs do_libc_backend_once multilib libc_mode="${libc_mode}"
+    CT_Popd
+    CT_EndStep
+}
+
+# This backend builds the C library
+# Usage: do_libc_backend param=value [...]
+#   Parameter           : Definition                      : Type      : Default
+#   libc_mode           : 'startfiles' or 'final'         : string    : (none)
+do_libc_backend_once() {
+    local libc_mode
+    local -a extra_cflags
+    local -a extra_config
+    local src_dir="${CT_SRC_DIR}/${CT_LIBC}-${CT_LIBC_VERSION}"
+    local multi_dir multi_os_dir multi_root multi_flags multi_index multi_count
+    local multilib_dir
+    local hdr_install_subdir
+    local arg f l
+
+    for arg in "$@"; do
+        eval "${arg// /\\ }"
+    done
+
+    CT_DoStep INFO "Building for multilib ${multi_index}/${multi_count}: '${multi_flags}'"
+
     multilib_dir="/usr/lib/${multi_os_dir}"
     CT_SanitizeVarDir multilib_dir
     CT_DoExecLog ALL mkdir -p "${multi_root}${multilib_dir}"
 
+    extra_cflags=( ${multi_flags} )
+
     # From buildroot:
     # gcc constant folding bug with weak aliases workaround
     # See http://www.openwall.com/lists/musl/2014/05/15/1
@@ -87,7 +95,12 @@ do_libc_backend() {
 
     extra_config+=( "--enable-optimize=${CT_LIBC_MUSL_OPTIMIZE}" )
 
-    CT_mkdir_pushd "${CT_BUILD_DIR}/build-libc-${libc_mode}"
+    # Same problem as with uClibc: different variants sometimes have
+    # incompatible headers.
+    CT_DoArchMUSLHeaderDir hdr_install_subdir "${multi_flags}"
+    if [ -n "${hdr_install_subdir}" ]; then
+        extra_config+=( "--includedir=/usr/include/${hdr_install_subdir}" )
+    fi
 
     # NOTE: musl handles the build/host/target a little bit differently
     # then one would expect:
@@ -95,21 +108,19 @@ do_libc_backend() {
     #   host    : same as --target
     #   target  : the machine musl runs on
     CT_DoExecLog CFG                                      \
-    CFLAGS="${extra_cflags[@]}"             \
+    CFLAGS="${extra_cflags[*]}"                           \
     CROSS_COMPILE="${CT_TARGET}-"                         \
     ${src_dir}/configure                                  \
-        --host="${CT_TARGET}"               \
+        --host="${multi_target}"                          \
-        --target="${CT_TARGET}"             \
+        --target="${multi_target}"                        \
         --prefix="/usr"                                   \
         --libdir="${multilib_dir}"                        \
         --disable-gcc-wrapper                             \
         "${extra_config[@]}"
 
-    if [ "${libc_headers}" = "y" ]; then
+    if [ "${libc_mode}" = "startfiles" ]; then
         CT_DoLog EXTRA "Installing C library headers"
         CT_DoExecLog ALL ${make} DESTDIR="${multi_root}" install-headers
-    fi
-    if [ "${libc_startfiles}" = "y" ]; then
         CT_DoLog EXTRA "Building C library start files"
         CT_DoExecLog ALL ${make} DESTDIR="${multi_root}" \
             obj/crt/crt1.o obj/crt/crti.o obj/crt/crtn.o
@@ -118,7 +129,7 @@ do_libc_backend() {
         CT_DoExecLog ALL ${CT_TARGET}-gcc -nostdlib \
             -nostartfiles -shared -x c /dev/null -o "${multi_root}${multilib_dir}/libc.so"
     fi
-    if [ "${libc_full}" = "y" ]; then
+    if [ "${libc_mode}" = "final" ]; then
         CT_DoLog EXTRA "Cleaning up start files"
         CT_DoExecLog ALL rm -f "${multi_root}${multilib_dir}/crt1.o" \
             "${multi_root}${multilib_dir}/crti.o" \
@@ -130,6 +141,18 @@ do_libc_backend() {
 
         CT_DoLog EXTRA "Installing C library"
         CT_DoExecLog ALL ${make} DESTDIR="${multi_root}" install
+
+        # Convert /lib/ld-* symlinks to relative paths so that they are valid
+        # both on the host and on the target.
+        for f in ${multi_root}/ld-musl-*; do
+            [ -L "${f}" ] || continue
+            l=$( readlink ${f} )
+            case "${l}" in
+                ${multilib_dir}/*)
+                    CT_DoExecLog ALL ln -sf "../${l}" "${f}"
+                    ;;
+            esac
+        done
     fi
 
     CT_EndStep

scripts/build/libc/uClibc.sh

@@ -172,7 +172,7 @@ do_libc_backend_once() {
     # at the final stage (see the note below), we may already have the subdirectory
     # in /usr/include.
     CT_DoArchUClibcHeaderDir hdr_install_subdir "${multi_flags}"
-    if [ -n "$hdr_install_subdir" ]; then
+    if [ -n "${hdr_install_subdir}" ]; then
         CT_DoExecLog ALL cp -a "${multi_root}/usr/include" "${multi_root}/usr/include.saved"
     fi
 
@@ -236,7 +236,7 @@ do_libc_backend_once() {
 
     # Now, if installing headers into a subdirectory, put everything in its place.
     # Remove the header subdirectory if it existed already.
-    if [ -n "$hdr_install_subdir" ]; then
+    if [ -n "${hdr_install_subdir}" ]; then
         CT_DoExecLog ALL mv "${multi_root}/usr/include" "${multi_root}/usr/include.new"
         CT_DoExecLog ALL mv "${multi_root}/usr/include.saved" "${multi_root}/usr/include"
         CT_DoExecLog ALL rm -rf "${multi_root}/usr/include/${hdr_install_subdir}"