[En-Nut-Discussion] Ethernut 3 linking problem: multiple definitions and undefined references

[José Vallet]

Hello.

We are porting an existing application from Ethernut2 to Ethernut3 (with 
ethernut-4.4.0), and we are stuck with some linkings problems. The 
problems appear _only_ when we link the code for the ARM architecture, 
whereas for AVR everything goes smoothly.

They problems are:

* PROBLEM 1: multiple definitions of `_close', `_write', `_read' and 
`_open'.

The type of messages that we get from the linker are, for example, like 
this,  (shrinked for easier reading. The complete output follows at the 
end of the message)
__________________
/usr/arm-elf/lib/libc.a(syscalls.o): In function `_close':
../../../../.././newlib/libc/sys/arm/syscalls.c:432: multiple definition 
of `_close'
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(close.o):close.c:(.text+0x0): 
first defined here
/usr/arm-elf/bin/ld: Warning: size of symbol `_close' changed from 60 in 
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(close.o) to 16 in 
/usr/arm-elf/lib/libc.a(syscalls.o)
__________________

To my poor understanding it looks something like the linker has found 2 
different `_close' functions, one from NutOS at libnutcrt.a and the 
other from newlib at libc.a, and does not know which one to use.
I have read 
http://groups.google.com/group/osdeve_mirror_rtos_En-Nut-Discussion/browse_thread/thread/b6213c340dce6887?q=libnutcrt+multiple+definitions#07e22d1f0be9c758
which seems to be a similar problem, but I have still clouds in my mind. 
In the previous thread the use of the strdup() function triggered the 
linker problems, and it seems that the solution was to add an 
implementation of strdup() to the aplication code. In our case I don't 
know what function/s might be triggering the linker complaints, so I 
don't know what to include in our application code. And still I am not 
sure that this is what I should really do. Any hints are welcomed.


* PROBLEM 2: undefined reference to `NutTraceTerminal'

About the undefined reference to `NutTraceTerminal' the linker message is
__________________
../NutDAC/lib/libndterm.a(nut-cmds-term.o): In function 
`nut_cmds_register_cmds':
nut-cmds-term.c:(.text+0x30): undefined reference to `NutTraceTerminal'
__________________

do I have to do something special in Ethernut3 in order to use the trace 
utilities?

* PROBLEM 3: undefined reference to `end'
The message from the linker is
__________________
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o): 
In function `_sbrk':
syscalls.c:(.text+0xdc): undefined reference to `end'
__________________

this one left me even more puzzled.


Any hints are warmly welcomed.

Regards
José


Here I include the full linker output

______________
arm-elf-gcc PemCtrl_v2.o adc.o boardtemp.o dac.o expander.o hal.o 
ctrl_daemon.o -mcpu=arm7tdmi -nostartfiles 
-T/home/jose/ethernut/ethernut-4.4.0/arch/arm/ldscripts/at91_ram.ld 
-Wl,-Map=PemCtrl_v2.map,--cref,--no-warn-mismatch 
-L/home/jose/ethernut/ethernut-4.4.0-bld/lib -L../NutDAC/lib 
-Wl,--start-group /home/jose/ethernut/ethernut-4.4.0-bld/lib/nutinit.o 
-lnutpro -lnutfs -lnutarch -lnutnet -lnutos -lnutdev -lnutarch -lnutcrt 
-lm  -lndchal -lndsl -lndterm -lndnet -lspi  -Wl,--end-group -o 
PemCtrl_v2.elf
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o): 
In function `_close':
../../../../.././newlib/libc/sys/arm/syscalls.c:432: multiple definition 
of `_close'
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(close.o):close.c:(.text+0x0): 
first defined here
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/bin/ld: Warning: 
size of symbol `_close' changed from 60 in 
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(close.o) to 16 in 
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o)
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o): 
In function `_write':
../../../../.././newlib/libc/sys/arm/syscalls.c:333: multiple definition 
of `_write'
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(write.o):write.c:(.text+0x0): 
first defined here
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/bin/ld: Warning: 
size of symbol `_write' changed from 52 in 
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(write.o) to 112 
in 
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o)
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o): 
In function `_read':
../../../../.././newlib/libc/sys/arm/syscalls.c:228: multiple definition 
of `_read'
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(read.o):read.c:(.text+0x0): 
first defined here
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/bin/ld: Warning: 
size of symbol `_read' changed from 52 in 
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(read.o) to 104 in 
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o)
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o): 
In function `_open':
../../../../.././newlib/libc/sys/arm/syscalls.c:410: multiple definition 
of `_open'
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(open.o):open.c:(.text+0x0): 
first defined here
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/bin/ld: Warning: 
size of symbol `_open' changed from 172 in 
/home/jose/ethernut/ethernut-4.4.0-bld/lib/libnutcrt.a(open.o) to 32 in 
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o)
../NutDAC/lib/libndterm.a(nut-cmds-term.o): In function 
`nut_cmds_register_cmds':
nut-cmds-term.c:(.text+0x30): undefined reference to `NutTraceTerminal'
/usr/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/libc.a(syscalls.o): 
In function `_sbrk':
syscalls.c:(.text+0xdc): undefined reference to `end'
collect2: ld returned 1 exit status
make[1]: *** [PemCtrl_v2.elf] Error 1