The old story:
- test program works, configure another library (openamp) into the BSP, and the rebuild fails
- remove openamp (and libmetal - which is pulled in gratis) from the BSP config and the rebuild still fails
- provide stub routines, at the bottom of main.c, and all is *well*
The test program is an evolved version of the LwIp demo [XAPP1026] running on a Zybo - which seems to run OK
The references which require stubs are _write called from _write_r in writer.c, _read and _close with similar call histories
The linker error report is around 200 characters long - a specimen tail is " /newwlib/libc/reent/writer.c:58:undefined reference to _write"
Bug, finger trouble, known issue, etc ?