Enhance 3rd party libc support

[nashif]

Using newlib by default across the project is currently not possible due to type conflicts. Zephyr should build with the newlib that comes with the Zephyr SDK and any newlib that comes pre-integrated with 3rd party toolchains.

Beside newlib, we need to support any 3rd libc and not limit the support to newlib and the minimal libc in the zephyr tree. A few options were discussed and being explored:

• make newlib zephyr aware
• Use PRI macro for 32bit integer types
• Make types in Zephyr compatible with newlib
• etc.

A few bugs are open that are related to this issue:

• kernel: Use accurate tick/ms conversion if clock rate is set at runtime #8920
• Make newlib libc the default c library #3102
• esp32: newlibc errors #1495
• newlib support in zephyr is untested and very broken #7441
• open-amp: enable C library cause open-amp\open-amp\lib\common\sh_mem.c compile error #8104

[nashif]

@galak @carlescufi @dleach02 FYI

[nashif]

I have just found what appears like a bug in our Zephyr SDK configuration. The toolchain does not expose any headers like unistd.h or sys/types.h, unlike any other toolchain we use. for example when you build with xtools or arm embedded toolchain, all the headers are available to zephyr, not with the Zephyr SDK forcing us to add all of those headers into the minimal libc in a non-compatible way.

This PR #8944 add the missing include

[nashif]

more issues #7441

[cfriedt]

@nashif - This can probably be closed now, no?

[stephanosio]

This can probably be closed now, no?

@cfriedt technically, this issue is not resolved.

make newlib zephyr aware

zephyrproject-rtos/sdk-ng#350

Use PRI macro for 32bit integer types
Make types in Zephyr compatible with newlib

#46032

[zephyrbot]

Hi @stephanosio,

This issue, marked as an Enhancement, was opened a while ago and did not get any traction. It was just assigned to you based on the labels. If you don't consider yourself the right person to address this issue, please re-assing it to the right person.

Please take a moment to review if the issue is still relevant to the project. If it is, please provide feedback and direction on how to move forward. If it is not, has already been addressed, is a duplicate, or is no longer relevant, please close it with a short comment explaining the reason.

@nashif you are also encouraged to help moving this issue forward by providing additional information and confirming this request/issue is still relevant to you.

Thanks!

[stephanosio]

Closing since Zephyr is currently compatible with various third-party C libraries without any major issues.