companion_libs: Make picolibc build compatible with 1.8.10

Picolibc 1.8.10 reworked the configuration option for single/multi
thread support and removed some unused options for exit handler
support.

Map LIBC_PICOLIBC_MULTITHREAD to the new single-thread option or the old
newlib-retargetable-locking+newlib-multithread options depending on whether
the picolibc version knows about the single-thread option.

Remove support for newlib-register-fini, newlib-atexit-dynamic-alloc,
newlib-global-atexit and lite-exit options as all of those relate to
the legacy exit handler code. There hasn't ever been any way to enable
this using crosstool-ng, so none of these options have ever done
anything.

The help strings for each of of the unused configuration variables
have been updated.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 42 insertions, 11 deletions

diff --git a/config/libc/picolibc.in b/config/libc/picolibc.in
index 6c4c6cac..c3014b11 100644
--- a/config/libc/picolibc.in
+++ b/config/libc/picolibc.in
@@ -40,31 +40,47 @@ config LIBC_PICOLIBC_IO_C99FMT
 
 config LIBC_PICOLIBC_REGISTER_FINI
     bool
-    prompt "Enable finalization function registration using atexit"
+    prompt "Enable finalization function registration using atexit [unused]"
     help
         Enable finalization function registration using atexit.
 
+	This would be used when building with the legacy newlib exit
+	handling code which cannot be enabled in crosstool-ng, so
+	this option doesn't do anything.
+
 config LIBC_PICOLIBC_ATEXIT_DYNAMIC_ALLOC
     bool
-    prompt "Enable dynamic allocation of atexit entries"
+    prompt "Enable dynamic allocation of atexit entries [unused]"
     help
         Enable dynamic allocation of atexit entries.
 
+	This would be used when building with the legacy newlib exit
+	handling code which cannot be enabled in crosstool-ng, so
+	this option doesn't do anything.
+
 config LIBC_PICOLIBC_GLOBAL_ATEXIT
     bool
-    prompt "Enable atexit data structure as global variable"
+    prompt "Enable atexit data structure as global variable [unused]"
     help
         Enable atexit data structure as global variable, instead
         of being thread-local.
 
+	This would be used when building with the legacy newlib exit
+	handling code which cannot be enabled in crosstool-ng, so
+	this option doesn't do anything.
+
 config LIBC_PICOLIBC_LITE_EXIT
     bool
-    prompt "Enable lite exit"
+    prompt "Enable lite exit [unused]"
     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.
 
+	This would be used when building with the legacy newlib exit
+	handling code which cannot be enabled in crosstool-ng, so
+	this option doesn't do anything.
+
 config LIBC_PICOLIBC_MULTITHREAD
     bool
     prompt "Enable support for multiple threads"
@@ -74,12 +90,15 @@ config LIBC_PICOLIBC_MULTITHREAD
 
 config LIBC_PICOLIBC_RETARGETABLE_LOCKING
     bool
-    prompt "Enable retargetable locking"
+    prompt "Enable retargetable locking [unused]"
     default y
     help
         Enable retargetable locking to allow the operating system to override
         the dummy lock functions defined within picolibc.
 
+	This value was always required to match
+	LIBC_PICOLIBC_MULTITHREAD, so it is no longer used.
+
 config LIBC_PICOLIBC_EXTRA_SECTIONS
     bool
     prompt "Place each function & data element in their own section"
diff --git a/scripts/build/companion_libs/340-picolibc.sh b/scripts/build/companion_libs/340-picolibc.sh
index 94bdaad9..bef72e0f 100644
--- a/scripts/build/companion_libs/340-picolibc.sh
+++ b/scripts/build/companion_libs/340-picolibc.sh
@@ -26,13 +26,7 @@ do_picolibc_common_install() {
 
     yn_args="IO_C99FMT:io-c99-formats
 IO_LL:io-long-long
-REGISTER_FINI:newlib-register-fini
 NANO_MALLOC:newlib-nano-malloc
-ATEXIT_DYNAMIC_ALLOC:newlib-atexit-dynamic-alloc
-GLOBAL_ATEXIT:newlib-global-atexit
-LITE_EXIT:lite-exit
-MULTITHREAD:newlib-multithread
-RETARGETABLE_LOCKING:newlib-retargetable-locking
     "
 
     for ynarg in $yn_args; do
@@ -48,6 +42,24 @@ RETARGETABLE_LOCKING:newlib-retargetable-locking
         fi
     done
 
+    # Check how picolibc wants threading support to be specified
+
+    if grep -q single-thread "${CT_SRC_DIR}/picolibc/meson_options.txt"; then
+	if [ "${CT_LIBC_PICOLIBC_MULTITHREAD}" = "y" ]; then
+	    picolibc_opts+=("-Dsingle-thread=false")
+	else
+	    picolibc_opts+=("-Dsingle-thread=true")
+	fi
+    else
+	if [ "${CT_LIBC_PICOLIBC_MULTITHREAD}" = "y" ]; then
+	    picolibc_opts+=("-Dnewlib-retargetable-locking=true")
+	    picolibc_opts+=("-Dnewlib-multithread=true")
+	else
+	    picolibc_opts+=("-Dnewlib-retargetable-locking=false")
+	    picolibc_opts+=("-Dnewlib-multithread=false")
+	fi
+    fi
+
     [ "${CT_LIBC_PICOLIBC_EXTRA_SECTIONS}" = "y" ] && \
         CT_LIBC_PICOLIBC_TARGET_CFLAGS="${CT_LIBC_PICOLIBC_TARGET_CFLAGS} -ffunction-sections -fdata-sections"