[lwip-users] lwip PPP malloc problem

[Rainer Thaden]

Dear all,

I am using lwIP 1.3.2 on a Stellaris LM3S6965 processor together with
FreeRTOS for UDP communication over ethernet.
lwIP is configured not to use malloc, so is FreeRTOS. Both use their own
heap implementation.
Everything is running as it should up to this point.

Since I need to communicate over serial ports, too, I activated PPP
support in lwipopts.h.
Now, the linker complains about undefined references to _sbrk which (to
me) is a sign for a call to malloc in the libc somewhere.
I do not use malloc anywhere else, so I didn't provide my own
implementation of _sbrk.
If I deactivate PPP support again, the complaints are gone.

I couldn't find any direct malloc call in the PPP sources. I also looked
through the c-preprocessed sources to have all macro substitutions done
before searching, but couldn't find it.
The linker map file also doesn't provide any clue.

Any ideas how to get rid of this?

Thanks in advance,

Rainer