nuttx/Documentation
Marco Casaroli 72f088ea8f arch/arm: Reserve r10 via ARCHCFLAGS and hoist the PIC module flags.
Toolchain.defs adds --fixed-r10 to CFLAGS under CONFIG_PIC, but nearly
every board Make.defs includes that file and then assigns

  CFLAGS := $(ARCHCFLAGS) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) ...

with ':=', which discards it.  266 of the 269 ARM board files assign
CFLAGS that way; the remaining three delegate to a shared makefile that
does the same thing.

The flag is what keeps the base firmware from allocating r10, the
register a PIC module reaches its own data through.  Losing it is silent
and the symptom is remote from the cause: the build succeeds, and only a
callback from base firmware into module code -- qsort() with a module
comparison function is the standard case -- misbehaves, reading its data
through a register the firmware has since felt free to reuse.

Adding it to ARCHCFLAGS puts it on the far side of that ':=', which
re-expands ARCHCFLAGS, so every board picks it up with no board changes
at all.

A module is the other side of the --fixed-r10 contract: it gets r10 via
-mpic-register=r10, and GCC rejects both on one command line with
"unable to use 'r10' for PIC register".  Every ARM board carried the
same three lines to set that up:

  ARCHPICFLAGS = -fpic -msingle-pic-base -mpic-register=r10
  CPICFLAGS = $(ARCHPICFLAGS) $(CFLAGS)
  CXXPICFLAGS = $(ARCHPICFLAGS) $(CXXFLAGS)

They move to arch/arm/src/common/Toolchain.defs, which also filters
--fixed-r10 back out of CPICFLAGS, CXXPICFLAGS, CELFFLAGS and
CXXELFFLAGS in one place instead of each board having to know about the
interaction.  ARCHPICFLAGS uses '?=' and the derived flags use deferred
'=', so a board can still override or append after including the file,
and CFLAGS is whatever the board finally set it to.

Two boards keep a definition because they genuinely differ: am67 adds
-ffixed-r10 and tiva conditionally adds -mno-pic-data-is-text-relative.
tlsr82 previously appended -fpic to an unset variable, so only -fpic
ever reached its compiler; it now inherits the standard set, verified
against tc32-elf-gcc 4.5.1.tc32-elf-1.5 (Telink TC32 v2.0), whose
ARM-derived backend honors -msingle-pic-base and -mpic-register=r10.
The mps2, mps3, qemu-armv7a, qemu-armv7r, fvp and mcx-nxxx families
referenced ARCHPICFLAGS without ever defining it, so their CPICFLAGS
carried no PIC flags at all; they get the standard set too.

Also adds the missing space in

  CXXELFFLAGS = $(CXXFLAGS)-fvisibility=hidden -mlong-calls

which ran the last token of CXXFLAGS into -fvisibility=hidden, yielding
a single malformed token such as -DNDEBUG-fvisibility=hidden.

Also exempts the pre-existing "*.siz" gsize comment in Toolchain.defs
from codespell, which reads "siz" as a misspelling and fires for any
patch touching the file, since checkpatch scans whole files rather than
changed lines.

Before, with CONFIG_PIC=y:  CFLAGS has --fixed-r10: NO
After:                      CFLAGS has --fixed-r10: YES
                            CPICFLAGS/CELFFLAGS:    filtered out

Assisted-by: Claude Code:claude-opus-4-8
Assisted-by: Claude Code:claude-fable-5
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
2026-07-24 13:17:12 +02:00
..
_extensions
_static
_templates
applications Documentation: PBKDF2 login docs, board Kconfig, and CI password 2026-07-21 20:19:14 +08:00
components arch/arm: Reserve r10 via ARCHCFLAGS and hoist the PIC module flags. 2026-07-24 13:17:12 +02:00
contributing !arch/stm32: move stm32l1 and finalize the directory split 2026-06-24 14:54:44 -03:00
debugging Documentation: Add documentation of SCHED_DUMP_TASKS and SCHED_DUMP_STACK 2026-06-09 08:04:54 -04:00
faq !boards: Remove NSH_ARCHINIT and board_app_initialize 2026-05-02 18:36:46 +08:00
guides arch/arm/src/stm32: unify pulse count driver into common/stm32 2026-07-12 09:35:51 +08:00
implementation Documentation: Fix kernel module wording. 2026-07-05 19:43:23 +02:00
introduction
logos
platforms documentation: add Python defconfig to esp32p4-tab5 board 2026-07-22 17:58:01 +08:00
quickstart Documentation: fill in pass1 directory description in organization.rst 2026-07-06 10:18:42 -03:00
reference arch/avr/src/avrdx/avrdx_delay: add custom up_udelay function 2026-06-12 09:55:11 -04:00
ReleaseNotes Documentation: add NuttX 13.0.0 release notes 2026-06-25 19:50:07 +08:00
standards libc/unistd: add getgroups() 2026-06-24 14:55:11 -03:00
testing Documentation/testing: Document MemBrowse integration 2026-06-19 12:21:54 -03:00
.gitignore
conf.py Documentation: conf: Ignore .venv 2026-05-29 01:26:21 +08:00
glossary.rst
index.rst docs/security: Add Security section to the documentation. 2026-01-06 02:17:20 +08:00
known-warnings.txt
legacy_README.md style: Fix "the the" typo across the codebase. 2026-03-23 11:07:49 +01:00
make.bat
Makefile doc: Improve sphinx build time + add autobuild help info. 2026-01-27 09:50:55 +08:00
Pipfile docs/plantuml: Add PlantUML support to Documentation build 2026-02-15 08:47:23 +01:00
Pipfile.lock build(deps): bump starlette from 1.0.1 to 1.3.1 in /Documentation 2026-06-18 12:49:49 -04:00
security.rst docs/security: Add Security section to the documentation. 2026-01-06 02:17:20 +08:00
substitutions.rst