Hello Peter, On 7/8/20 11:02 PM, Peter Mamonov wrote: >>> I tried to build MicroPython using barebox toolchain and found a number of >>> conflicts between barebox and compiler headers. Below you will find the >>> patch >>> which demostrates some of them. In this particular example the problem >>> arises >>> due to simultaneous inclusion of some compiler headers along with barebox >>> version of `strings.h`, which in turn includes barebox analogs of those >>> headers >>> from `include/linux`. I belive there should be a segregation between >>> headers in >>> `include` and in `include/linux`, i.e. headers from `include/` should not >>> reference <linux/*.h> headers. Yet I understand this is somewhat >>> problematic. >>> What do you think? >> >> barebox code shouldn't make use of any compiler headers at all, except for >> <stdarg.h>. >> The only exception are arch/sandbox/os and scripts/, which reference libc >> headers. >> Everything else should comes out of barebox' include/ directory. >> >> If you have foreign code that you want to port into barebox, either modify it >> to use barebox headers or change the include order when building it to use >> _local_ >> versions of the headers it requires. > > Ok, I've got your point. Yet I want to point out that addition of *unmodified* > code in a form of git submodule would greatly simplify further support of > this > port. Unfortunately modifying include order will not help in this case, > since, > for example, both `barebox/include/linux/stddef.h` (included from > `barebox/include/string.h` via <linux/string.h>, etc.) and > `/usr/lib/gcc-cross/<ARCH>-linux-gnu/X/include/stdbool.h` define > `true`/`false` > macros. On the other hand `/usr/include/linux/stddef.h` and > `/usr/lib/gcc/<ARCH>-linux-gnu/X/include/stdbool.h` coexist in GNU/Linux > system > nicely, since no header from `/usr/include/` does reference <linux/*.h> > headers.
Even if our headers didn't clash, our symbols might. You want to use the same declaration/prototype everywhere a symbol is used. If you have external code that uses, say, <string.h>. You write your own string.h, and ensure it's first in include path for all the code in the HAL (or w/e) directory you have. In that file you could have your wrappers and then #include_next <stdio.h> if needed. If you have global symbols clashing in incompatible ways, you could perhaps postprocess the micropython object code with objcopy to give all symbols a micropython_ prefix..? The proper abstraction is probably to have a module, but that seems only supported on ARM. >>> diff --git a/commands/types_conflict.c b/commands/types_conflict.c >>> new file mode 100644 >>> index 0000000000..70fee8d6f4 >>> --- /dev/null >>> +++ b/commands/types_conflict.c >>> @@ -0,0 +1,12 @@ >>> +#include <stdbool.h> >>> +#include <stdint.h> >>> +#include <stddef.h> >>> + >>> +#include <string.h> >> >> barebox (except sandbox) is meant to be compiled with freestanding C >> implementations >> that aren't required to provide a <string.h>. So no barebox code should >> depend on >> compiler-provided <string.h>. > > Actually `string.h` comes from barebox's `include/` dir, while `std*.h` come > from compiler's include dir. > > > PS: By the way, do you think Barebox will benefit from importing MicroPython > (https://micropython.org/) and exposing some of Barebox APIs to it? We have setjmp/longjmp on all architectures now, so it should make porting MicroPython easier. I probably wouldn't use it, but I guess it could have some educational value for people interested to go from MicroPython + Microcontroller to an application processor..? It'd be cool to have for sure ;) Cheers, Ahmad > Regards, > Peter -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox
