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Diffstat (limited to 'docs/develop/natmod.rst')
| -rw-r--r-- | docs/develop/natmod.rst | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/docs/develop/natmod.rst b/docs/develop/natmod.rst index 18678eaefb..2ccd832885 100644 --- a/docs/develop/natmod.rst +++ b/docs/develop/natmod.rst @@ -81,7 +81,14 @@ Linker limitation: the native module is not linked against the symbol table of t full MicroPython firmware. Rather, it is linked against an explicit table of exported symbols found in ``mp_fun_table`` (in ``py/nativeglue.h``), that is fixed at firmware build time. It is thus not possible to simply call some arbitrary HAL/OS/RTOS/system -function, for example. +function, for example, unless that resides at a fixed address. In that case, the path +of a linkerscript containing a series of symbol names and their fixed address can be +passed to ``mpy_ld.py`` via the ``--externs`` command line argument. That way symbols +appearing in the linkerscript will take precedence over what is provided from object +files, but at the moment the object files' implementation will still reside in the +final MPY file. The linkerscript parser is limited in its capabilities, and is +currently used only for parsing the ESP8266 port ROM symbols list (see +``ports/esp8266/boards/eagle.rom.addr.v6.ld``). New symbols can be added to the end of the table and the firmware rebuilt. The symbols also need to be added to ``tools/mpy_ld.py``'s ``fun_table`` dict in the |