How to properly link ed25519-donna with c++? (where is the -mbits flag?)

Question

I've found this great question and this one which seems even greater where productivity's concerned.

To use the code, link against ed25519.o -mbits and:

#include "ed25519.h"

First, I can't find the -mbits flag. More importantly is it possible to use the technique in the more productive answer?

I was afraid to considering the importance, but I tried to use the techniques above combined with recommendations from the docs without the -mbits flag

g++  -o server ed25519-donna-master/ed25519.o myserver -std=c++0x -I ~/myserver -D_WEBSOCKETPP_CPP11_STL_ -D_WEBSOCKETPP_NO_CPP11_REGEX_ -lboost_regex -lboost_system -L/usr/lib -lssl -lcrypto -pthread -lconfig++ -lpqxx -lboost_thread

and this is the result

myserver: In function `_start':
(.text+0x0): multiple definition of `_start'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 2 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 3 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 4 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 5 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 6 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 7 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 9 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 10 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 11 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 12 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 13 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 14 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 15 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 16 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 17 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 18 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 19 has invalid symbol index 21
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o:/build/buildd/eglibc-2.17/csu/../sysdeps/x86_64/start.S:119: first defined here
myserver: In function `_fini':
(.fini+0x0): multiple definition of `_fini'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_info): relocation 0 has invalid symbol index 7
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_info): relocation 1 has invalid symbol index 8
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_info): relocation 2 has invalid symbol index 9
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 0 has invalid symbol index 4
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 1 has invalid symbol index 4
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 2 has invalid symbol index 5
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_ranges): relocation 3 has invalid symbol index 5
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o:(.fini+0x0): first defined here
myserver: In function `__data_start':
(.data+0x0): multiple definition of `__data_start'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o:(.data+0x0): first defined here
myserver: In function `_init':
(.init+0x0): multiple definition of `_init'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_line): relocation 0 has invalid symbol index 4
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crti.o(.debug_line): relocation 1 has invalid symbol index 5
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o:/build/buildd/eglibc-2.17/csu/../sysdeps/x86_64/crti.S:64: first defined here
myserver: In function `__data_start':
(.data+0x8): multiple definition of `__dso_handle'
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o:(.data+0x0): first defined here
myserver:(.rodata+0x0): multiple definition of `_IO_stdin_used'
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o:(.rodata.cst4+0x0): first defined here
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o:(.tm_clone_table+0x0): multiple definition of `__TMC_END__'
myserver:(.data+0x38): first defined here
/usr/bin/ld: error in myserver(.eh_frame); no .eh_frame_hdr table will be created.
collect2: error: ld returned 1 exit status

I think I need the -mbits flag, but I can't find it. There are a few mbit type flags for gcc. Can one of those be used? If so, which one?

@JonathonReinhart I apologize Jonathon Reinhart for neglecting those tags, and thank you for looking! I have added `gcc` and `g++`. — , Feb 18 '14 at 15:34
In your C++ code, did you do this: `extern "C" { #include "ed25519.h" }`? — Markku K., Feb 18 '14 at 16:37
@MarkkuK. Thank you Markku K.! Yes, I tried both with and without; interestingly, the errors are the same. Do you know what should be done about the `-mbits` flag? Thank you so very much in advance! — , Feb 18 '14 at 16:40
That seems to mean use `-m64` on a 64-bit system and use `-m32` on a 32-bit system. Looks like `-m64` for you. — Markku K., Feb 18 '14 at 18:06
@MarkkuK. Thank you for the information on mbits! The errors go away if I leave the `include` and remove the `ed25519.o`. As soon as I can test, I will post an answer. — , Feb 18 '14 at 18:09
Actually, I just looked at your compile command. Are you trying to create a new executable called 'server', by linking ed25519.o with an existing executable called 'myserver'? That is probably the source of most of your problems -- you need to link ed25519.o with the .o files used to create 'myserver' instead. — Markku K., Feb 18 '14 at 18:10
@MarkkuK. That did it! Thank you very much Markku K.! Would you mind upgrading to an answer? Thank you so very much in advance Markku K.! — , Feb 18 '14 at 18:28

score 1 · Accepted Answer · answered Feb 18 '14 at 18:38

Are you trying to create a new executable called 'server', by linking ed25519.o with an existing executable called 'myserver'? That is probably the source of most of your problems -- you need to link ed25519.o with the .o files used to create 'myserver' instead.

As far as the -mbits option, I think they mean use -m32 or -m64, depending on the architecture of the machine you are compiling on. So, for you that means use -m64.

How to properly link ed25519-donna with c++? (where is the -mbits flag?)

1 Answers1