build: Add support for checking an llext build at compile time

This commit adds compile-time checking of the sketch to verify that all
symbols not directly resolved in the sketch are defined in the Zephyr
core. This reuses the 'linked' logic, but defines the llext-specific
symbols only.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Author: pillo79

.gitignore

@@ -6,4 +6,5 @@ llext-edk/
 cflags.txt
 cxxflags.txt
 includes.txt
-provides.ld
+syms-llext.ld
+syms-linked.ld

boards.txt

@@ -450,7 +450,7 @@ portentac33.menu.mode.linked=linked
 portentac33.menu.mode.linked.build.extra_ldflags=-lc -lm -lgcc -L{build.variant.path} -Wl,--wrap=random -Wl,--wrap=calloc -Wl,--wrap=free -Wl,--wrap=malloc -Wl,--wrap=realloc 
 portentac33.menu.mode.linked.build.llext_link_flags=
 portentac33.menu.mode.linked.build.suffix=_linked
-portentac33.menu.mode.linked.build.ldscript={runtime.platform.path}/variants/_linked/linker_script.ld
+portentac33.menu.mode.linked.build.link_mode=linked
 portentac33.menu.mode.linked.upload.extension=bin-zsk.bin
 portentac33.menu.mode.linked.postbuild_mode=-prelinked
 

extra/build.sh

@@ -91,6 +91,7 @@ done
 
 # Generate the provides.ld file for linked builds
 echo "Generating exported symbol scripts"
+extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -L > ${VARIANT_DIR}/syms-llext.ld
 extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -LF \
 	"+kheap_llext_heap" \
 	"+kheap__system_heap" \
@@ -100,6 +101,6 @@ extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -LF \
 	"free=__wrap_free" \
 	"realloc=__wrap_realloc" \
 	"calloc=__wrap_calloc" \
-	"random=__wrap_random" > ${VARIANT_DIR}/provides.ld
+	"random=__wrap_random" > ${VARIANT_DIR}/syms-linked.ld
 
 cmake -P extra/gen_arduino_files.cmake $variant

extra/package_core.inc

@@ -13,5 +13,4 @@ README.md
 doc/
 cores/
 libraries/
-variants/_llext/
-variants/_linked/
+variants/_ldscripts/

platform.txt

@@ -49,9 +49,17 @@ compiler.zephyr.extra_ldflags=-lstdc++ -lsupc++
 # this can be overriden in boards.txt
 build.extra_flags=
 build.extra_ldflags=
+build.link_mode=llext
 compiler.zephyr=
 
-build.ldscript={runtime.platform.path}/variants/_llext/linker_script.ld
+build.ldscript.path={runtime.platform.path}/variants/_ldscripts
+build.link_command="{compiler.path}{compiler.c.elf.cmd}" "-L{build.path}" {compiler.c.elf.flags} {compiler.c.elf.extra_flags} {build.extra_flags} {build.extra_ldflags} {compiler.zephyr.common_ldflags} --specs=picolibc.specs --specs=nosys.specs {compiler.ldflags} {object_files} -Wl,--start-group "{build.path}/{archive_file}" {compiler.zephyr} {compiler.zephyr.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group
+build.link_command.check-llext={build.link_command}
+build.link_args.check-llext="-T{build.variant.path}/syms-llext.ld" "-T{build.ldscript.path}/memory-check.ld" "-T{build.ldscript.path}/build-linked.ld" -o /dev/null
+build.link_args.build-llext="-T{build.ldscript.path}/build-llext.ld"
+build.link_args.build-linked="-T{build.variant.path}/syms-linked.ld" "-T{build.ldscript.path}/memory-linked.ld" "-T{build.ldscript.path}/build-linked.ld"
+build.link_args.build-common="-Wl,-Map,{build.path}/{build.project_name}.map" -o "{build.path}/{build.project_name}_debug.elf"
+
 build.llext_link_flags=-r -e main
 build.extra_extra_ldflags=
 build.suffix=
@@ -99,7 +107,9 @@ recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} -DARDUIN
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"
 
 ## Combine gc-sections, archives, and objects
-recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}"  "-L{build.path}" {compiler.c.elf.flags} {compiler.c.elf.extra_flags} {build.extra_flags} {build.extra_ldflags} {compiler.zephyr.common_ldflags} "-T{build.ldscript}" "-Wl,-Map,{build.path}/{build.project_name}.map" --specs=picolibc.specs --specs=nosys.specs {compiler.ldflags} -o "{build.path}/{build.project_name}_debug.elf" {object_files} -Wl,--start-group "{build.path}/{archive_file}" {compiler.zephyr} {compiler.zephyr.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group
+recipe.c.combine.1.pattern={build.link_command.check-{build.link_mode}} {build.link_args.check-{build.link_mode}}
+recipe.c.combine.2.pattern={build.link_command} {build.link_args.build-{build.link_mode}} {build.link_args.build-common}
+recipe.c.combine.pattern={recipe.c.combine.2.pattern}
 recipe.hooks.linking.postlink.1.pattern="{compiler.path}{build.crossprefix}strip" --strip-debug "{build.path}/{build.project_name}_debug.elf" -o "{build.path}/{build.project_name}.elf"
 
 ## Create eeprom

variants/_linked/linker_script.ld renamed to variants/_ldscripts/build-linked.ld

@@ -1,18 +1,5 @@
-INCLUDE "provides.ld"
-
-MEMORY
-{
-    /* 16 below compensates for the zsk header that is added before the .bin */
-    FLASH (rx) : ORIGIN = _sketch_start + 16, LENGTH = _sketch_max_size - 16
-    RAM (rwx) : ORIGIN = kheap_llext_heap, LENGTH = kheap_llext_heap_size
-}
-
-PROVIDE(__heap_start = kheap__system_heap);
-PROVIDE(__heap_end = kheap__system_heap + kheap__system_heap_size);
-
 ENTRY(entry_point)
 SECTIONS {
-
     /DISCARD/ : {
         *(.ARM.attributes)
         *(.ARM.attributes.*)

variants/_llext/linker_script.ld renamed to variants/_ldscripts/build-llext.ld

@@ -0,0 +1,8 @@
+MEMORY
+{
+    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 0x10000000
+    RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 0x10000000
+}
+
+PROVIDE(__heap_start = 0x40000000);
+PROVIDE(__heap_end = 0x50000000);

variants/_ldscripts/memory-check.ld

@@ -0,0 +1,9 @@
+MEMORY
+{
+    /* 16 below compensates for the zsk header that is added before the .bin */
+    FLASH (rx) : ORIGIN = _sketch_start + 16, LENGTH = _sketch_max_size - 16
+    RAM (rwx) : ORIGIN = kheap_llext_heap, LENGTH = kheap_llext_heap_size
+}
+
+PROVIDE(__heap_start = kheap__system_heap);
+PROVIDE(__heap_end = kheap__system_heap + kheap__system_heap_size);