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cederom
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With CONFIG_LTO_FULL (GCC), LD is the compiler driver, and a loadable module (and a program of a kernel build) is linked with it, because MODULELD defaults to LD. Application.mk gave the program attributes as "--defsym nx_stacksize=...", and gcc stopped with "unrecognized command-line option '--defsym'". Where Application.mk sets MODLDFLAGS, it now also sets MODDEFSYM: "-Wl,--defsym=" when MODULELD is gcc or clang, and "--defsym=" for ld. A link with ld gets "--defsym=sym=value" in place of "--defsym sym value", which GNU ld and ld.lld read the same way. Assisted-by: Claude Code:claude-opus-5-5 Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
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October 20, 2026 23:06
🔗 Cross-repo PR dependenciesThe read-only Build run reported the following dependent PR(s) and fetched head SHA(s): CI run: https://github.com/apache/nuttx-apps/actions/runs/39509862159 |
xiaoxiang781216
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Summary
With
CONFIG_LTO_FULL(GCC),LDis the compiler driver, and the Make build links each loadable module (and each program of a kernel build) with it, becauseMODULELDdefaults toLD.Application.mkgives the program attributes as--defsym nx_stacksize=..., and gcc stops withunrecognized command-line option '--defsym'.Where
Application.mksetsMODLDFLAGS, it now also setsMODDEFSYM:-Wl,--defsym=whenMODULELDis gcc or clang, and--defsym=for ld.The other part of the earlier version (
-flinker-output=nolto-reland the module options inMake.defs) moved to NuttX, where the flags are first set, as asked in the review: apache/nuttx#20846. A module with LTO links only with both PRs.depends-on: apache/nuttx/pull/20846
Impact
Only builds with
CONFIG_LTO_FULLand a module or a kernel build: the modules link. A link with ld gets--defsym=sym=valuein place of--defsym sym value, which GNU ld and ld.lld read the same way.Testing
qemu-armv8a:nsh(flat, Arm GNU 14.2, QEMU HVF) withCONFIG_LTO_FULL,CONFIG_ELF,CONFIG_EXECFUNCS_SYSTEM_SYMTABandCONFIG_EXAMPLES_HELLO=m, rebased on apps master: the link ofhellohas-Wl,--defsym=nx_stacksize=...and-Wl,--defsym=nx_priority=...and builds; with apache/nuttx#20846helloloads and printsHello, World!!(on nuttx master the module keeps LTO data only and fails withexec failed: 22). The earlier version ran the TLS tests and aLibrary.mkshared library with LTO onqemu-armv8a:nshandmps2-an500:nsh, and the same programs without LTO (--defsym=with ld).tools/checkpatch.sh -c -u -m -gpasses.