boards/rp23xx: Add an FDPIC configuration for the Pimoroni Pico Plus 2.

xipfs-fdpic is the xipfs configuration plus the FDPIC loader and the
fdpicxip demo, so that the fdpic and reject sections of the XIPFS test
suite have something to run.  It is the configuration the loader was
tested with, and until now none was in the tree: FDPIC needed a dozen
options set by hand, three of which are not obvious.

CONFIG_LIBC_ENVPATH and CONFIG_LDPATH_INITIAL, because a library named in
DT_NEEDED is opened by name and dlopen() searches LD_LIBRARY_PATH.  And
CONFIG_LIBC_ELF_HAVE_SYMTAB, because a library resolves its own imports
against the module registry's symbol table rather than the one exec()
supplies.

CONFIG_DEFAULT_TASK_STACKSIZE goes to 4096, from the board's 2048, and
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 with no
diagnostic at all; CONFIG_ELF_STACKSIZE is not set here because it
defaults to CONFIG_DEFAULT_TASK_STACKSIZE and so follows it to 4096.  The
XIPFS test task is sized from it directly, and at 2048 that task overflows
in printf partway through the module tests, so the suite stops mid-run
with no failure reported and no dump -- which reads as a loader bug rather
than as the test running out of stack.

Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>

Author: casaroli

Documentation/platforms/arm/rp23xx/boards/pimoroni-pico-2-plus/index.rst

@@ -177,6 +177,21 @@ xipfs
 XIPFS mounted on the on-board flash, with the ``xipfs`` command and the
 XIPFS test suite.
 
+xipfs-fdpic
+-----------
+
+Same as ``xipfs``, plus the FDPIC module loader and the
+``fdpicxip`` demo, so the ``fdpic`` and ``reject`` sections of the XIPFS
+test suite have something to run.  The demo carries its modules as
+committed byte arrays, so nothing beyond the ordinary ARM toolchain is
+needed to build it; rebuilding those from source needs
+``arm-uclinuxfdpiceabi`` binutils.  See :doc:`/components/fdpic`.
+
+``CONFIG_ELF_STACKSIZE`` is 4096 here rather than the 2048 the rest of
+the board's tasks use.  A module that calls into the firmware's printf
+family overflows 2048, and with no MPU that is a lockup rather than a
+diagnostic.
+
 xipfs-nxflat
 ------------
 

boards/arm/rp23xx/pimoroni-pico-2-plus/configs/xipfs-fdpic/defconfig

@@ -0,0 +1,66 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_NSH_ARGCAT is not set
+# CONFIG_NSH_CMDOPT_HEXDUMP is not set
+# CONFIG_NSH_DISABLE_DATE is not set
+# CONFIG_NSH_DISABLE_LOSMART is not set
+# CONFIG_STANDARD_SERIAL is not set
+CONFIG_ARCH="arm"
+CONFIG_ARCH_BOARD="pimoroni-pico-2-plus"
+CONFIG_ARCH_BOARD_COMMON=y
+CONFIG_ARCH_BOARD_PIMORONI_PICO_2_PLUS=y
+CONFIG_ARCH_CHIP="rp23xx"
+CONFIG_ARCH_CHIP_RP23XX=y
+CONFIG_ARCH_RAMVECTORS=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_BINFMT_CONSTRUCTORS=y
+CONFIG_BOARDCTL_RESET=y
+CONFIG_BOARD_LOOPSPERMSEC=10450
+CONFIG_BUILTIN=y
+CONFIG_DEBUG_FULLOPT=y
+CONFIG_DEBUG_SYMBOLS=y
+CONFIG_DEFAULT_TASK_STACKSIZE=4096
+CONFIG_ELF=y
+CONFIG_EXAMPLES_FDPICXIP=y
+CONFIG_EXAMPLES_HELLO=y
+CONFIG_EXECFUNCS_HAVE_SYMTAB=y
+CONFIG_EXECFUNCS_SYSTEM_SYMTAB=y
+CONFIG_FDPIC=y
+CONFIG_FS_PROCFS=y
+CONFIG_FS_PROCFS_REGISTER=y
+CONFIG_FS_XIPFS=y
+CONFIG_FS_XIPFS_FAULT_INJECT=y
+CONFIG_HAVE_CXX=y
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_INIT_STACKSIZE=16384
+CONFIG_LDPATH_INITIAL="/mnt/xipfs"
+CONFIG_LIBC_DLFCN=y
+CONFIG_LIBC_ELF_HAVE_SYMTAB=y
+CONFIG_LIBC_ENVPATH=y
+CONFIG_LIBC_EXECFUNCS=y
+CONFIG_MTD=y
+CONFIG_NFILE_DESCRIPTORS_PER_BLOCK=6
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_READLINE=y
+CONFIG_RAM_SIZE=532480
+CONFIG_RAM_START=0x20000000
+CONFIG_READLINE_CMD_HISTORY=y
+CONFIG_RP23XX_FLASH_MTD=y
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_HPWORK=y
+CONFIG_SCHED_WAITPID=y
+CONFIG_SIG_EVTHREAD=y
+CONFIG_START_DAY=9
+CONFIG_START_MONTH=2
+CONFIG_START_YEAR=2021
+CONFIG_SYSLOG_CONSOLE=y
+CONFIG_SYSTEM_NSH=y
+CONFIG_SYSTEM_XIPFS=y
+CONFIG_TESTING_FS_XIPFS=y
+CONFIG_TESTING_FS_XIPFS_MTD="/dev/rpflash"
+CONFIG_UART0_SERIAL_CONSOLE=y