nuttx/Documentation/os
Marco Casaroli f565c81c3b Documentation, boards/rp23xx: Describe FDPIC and add a test configuration.
Documentation/os/binfmt/fdpic.rst covers what an FDPIC module is and what
it adds over the position independent ELF support already in the tree, how
the loader places one, where shared libraries come from and how they are
found, which entry points resolve a function descriptor and the rules for
adding another, and how to build a module and a library.  A comparison
table places it against NXFLAT and PIC ELF, and the reference section
records the object layout and the relocations.

pimoroni-pico-2-plus:xipfs-fdpic is the configuration the series was tested
on: xipfs on the board's QSPI flash, the ELF loader with CONFIG_FDPIC, and
apps/examples/fdpicxip with apps/testing/fs/xipfs.

CONFIG_DEFAULT_TASK_STACKSIZE is 4096 there rather than the rp23xx default
of 2048.  Both sides of the loader need it: a module that calls into the
firmware's printf family overflows 2048, and with no MPU that is a lockup
rather than a diagnostic.  CONFIG_ELF_STACKSIZE follows it, and
apps/testing/fs/xipfs sizes its own task from it.

CONFIG_HAVE_CXXINITIALIZE is set because crt0 runs the constructors of a
module only with it, and the xipfs suite checks that they ran.

Assisted-by: Claude Code:claude-opus-5-5
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
2026-10-08 14:24:34 -03:00
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graphics
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app_vs_os.rst
build_modes.rst
build_modes.svg
conventions.rst
crypto.rst
index.rst
notifier.rst
nuttx.rst
openamp.rst
syscall.rst
system_map.svg
video.rst
wireless.rst