61 lines
2.9 KiB
ReStructuredText
61 lines
2.9 KiB
ReStructuredText
=====================================
|
||
``sotest`` Shared Library Module Test
|
||
=====================================
|
||
|
||
This example builds a small shared library module test case. The test shared
|
||
library is built using the relocatable ELF format and installed in a ROMFS file
|
||
system. At run time, the shared library is installed and exercised. Requires
|
||
``CONFIG_LIBC_DLFCN``. Other configuration options:
|
||
|
||
- ``CONFIG_EXAMPLES_SOTEST_DEVMINOR`` – The minor device number of the ROMFS block
|
||
driver. For example, the ``N`` in ``/dev/ramN``. Used for registering the RAM
|
||
block driver that will hold the ROMFS file system containing the ELF
|
||
executables to be tested. Default: ``0``.
|
||
|
||
- ``CONFIG_EXAMPLES_SOTEST_DEVPATH`` – The path to the ROMFS block driver device.
|
||
This must match ``EXAMPLES_ELF_DEVMINOR``. Used for registering the RAM block
|
||
driver that will hold the ROMFS file system containing the ELF executables to
|
||
be tested. Default: ``/dev/ram0``.
|
||
|
||
**Notes**:
|
||
|
||
1. ``CFLAGS`` should be provided in ``CMODULEFLAGS``. RAM and FLASH memory regions
|
||
may require long allcs. For ARM, this might be::
|
||
|
||
CMODULEFLAGS = $(CFLAGS) -mlong-calls
|
||
|
||
Similarly for C++ flags which must be provided in ``CXXMODULEFLAGS``.
|
||
|
||
2. Your top-level ``nuttx/Make.defs`` file must also include an appropriate
|
||
definition, ``LDMODULEFLAGS``, to generate a relocatable ELF object. With GNU
|
||
LD, this should include ``-r`` and ``-e <entry point>``.::
|
||
|
||
LDMODULEFLAGS = -r -e module_initialize
|
||
|
||
If you use GCC to link, you make also need to include ``-nostdlib``.
|
||
|
||
3. This example also requires ``genromfs``. ``genromfs`` can be build as part of the
|
||
nuttx toolchain. Or can built from the ``genromfs`` sources that can be found
|
||
in the NuttX tools repository (``genromfs-0.5.2.tar.gz``). In any event, the
|
||
``PATH`` variable must include the path to the ``genromfs`` executable.
|
||
|
||
4. ELF size: The ELF files in this example are, be default, quite large because
|
||
they include a lot of build garbage. You can greatly reduce the size of the
|
||
ELF binaries are using the ``objcopy --strip-unneeded`` command to remove
|
||
un-necessary information from the ELF files.
|
||
|
||
5. Simulator. You cannot use this example with the NuttX simulator on Cygwin.
|
||
That is because the Cygwin GCC does not generate ELF file but rather some
|
||
Windows-native binary format.
|
||
|
||
If you really want to do this, you can create a NuttX x86 buildroot toolchain
|
||
and use that be build the ELF executables for the ROMFS file system.
|
||
|
||
6. Linker scripts. You might also want to use a linker scripts to combine
|
||
sections better. An example linker script is at
|
||
``nuttx/libc/modlib/gnu-elf.ld``. That example might have to be tuned for your
|
||
particular linker output to position additional sections correctly. The GNU
|
||
LD ``LDMODULEFLAGS`` then might be::
|
||
|
||
LDMODULEFLAGS = -r -e module_initialize -T$(TOPDIR)/libc/modlib/gnu-elf.ld
|