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new 55130297110 arch/arm: Build a loadable module and a shared library as
FDPIC too.
55130297110 is described below
commit 551302971101e5a54eebd0c64c1e0d1164b49c77
Author: Marco Casaroli <[email protected]>
AuthorDate: Fri Sep 25 11:33:39 2026 +0200
arch/arm: Build a loadable module and a shared library as FDPIC too.
CONFIG_FDPIC teaches the ELF module path what an FDPIC object is, so an
application built as a module gets -mfdpic -fPIC and the
arm-uclinuxfdpiceabi linker. The loadable module path, which apps builds
with DYNLIB = y and which apps/Library.mk uses for a shared library, was
left as it was: a -r partial link with the stock linker. That leaves an
object with no dynamic section, so the loader has nothing to bind an import
to, and there is no way to build a library an FDPIC module can call.
Give that path the same treatment. CMODULEFLAGS and CXXMODULEFLAGS gain the
FDPIC compiler flags, and LDMODULEFLAGS links a shared object rather than a
partial one. The entry point is left to the caller, because a module is
entered at _start while a library is only ever called into.
CXXMODULEFLAGS is also defined for the first time. apps/Library.mk compiles
every C++ source of a shared library with it and no architecture defined it,
so those sources were compiled with no architecture flags at all.
Assisted-by: Claude Opus 5 (1M context) <[email protected]>
Signed-off-by: Marco Casaroli <[email protected]>
---
arch/arm/src/common/Toolchain.defs | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/arch/arm/src/common/Toolchain.defs
b/arch/arm/src/common/Toolchain.defs
index a1d65803263..c169e2d25ec 100644
--- a/arch/arm/src/common/Toolchain.defs
+++ b/arch/arm/src/common/Toolchain.defs
@@ -619,7 +619,10 @@ endif
# Loadable module definitions
+# CXXMODULEFLAGS is what apps/Library.mk compiles a C++ shared library with.
+
CMODULEFLAGS = $(CFLAGS) -fvisibility=hidden -mlong-calls # --target1-abs
+CXXMODULEFLAGS = $(CXXFLAGS) -fvisibility=hidden -mlong-calls
LDMODULEFLAGS = -r -T $(call CONVERT_PATH,$(TOPDIR)/libs/libc/elf/gnu-elf.ld)
# ELF module definitions
@@ -633,9 +636,11 @@ CELFFLAGS = $(filter-out --fixed-r9,$(CFLAGS))
-fvisibility=hidden \
CXXELFFLAGS = $(filter-out --fixed-r9,$(CXXFLAGS)) -fvisibility=hidden \
-mlong-calls
-# __dso_handle comes from crtbegin, which a module does not link
+# __dso_handle comes from crtbegin, which neither a module nor a shared
+# library links
CXXELFFLAGS += -fno-use-cxa-atexit
+CXXMODULEFLAGS += -fno-use-cxa-atexit
ifeq ($(CONFIG_PIC),y)
# ARCHCFLAGS, not CFLAGS: board Make.defs reassign CFLAGS with ':='
@@ -673,6 +678,20 @@ ifeq ($(CONFIG_FDPIC),y)
CXXELFFLAGS += -mfdpic -fPIC -Wa,--noexecstack
LDELFFLAGS += -m armelf_linux_fdpiceabi -shared -z now
+
+ # A loadable module and a shared library are the same kind of object here,
+ # so they are built the same way. The partial link the module path uses
+ # elsewhere leaves no dynamic section, and the loader has nothing to bind
+ # an import to.
+ #
+ # The entry point is left to the caller: a module is entered at _start,
+ # a library is only called into.
+
+ CMODULEFLAGS += -mfdpic -fPIC -Wa,--noexecstack
+ CXXMODULEFLAGS += -mfdpic -fPIC -Wa,--noexecstack
+
+ LDMODULEFLAGS = -m armelf_linux_fdpiceabi -shared -z now \
+ -T $(call CONVERT_PATH,$(TOPDIR)/libs/libc/elf/gnu-elf.ld)
else
CELFFLAGS += $(PICFLAGS) -mpic-register=r9
CXXELFFLAGS += $(PICFLAGS) -mpic-register=r9
