[Help me] A link error

[SCSoft]

ld give me a error message like this:
undefined reference to _functionname

in console:
ld -Ttext 0x10500 --oformat binary -o main.bin main.o timer.o task.o

timer.o:timer.c:(.text+0xc6): undefined reference to '_install'


in timer.c:
extern void install(void);

...
...
install();

[carbonBased]

You haven't told us where _install is defined. Is it being linked in?

Which platform/object format are you using? Certain ABIs do not prepend underscores, while others do.

--Jeff

[SCSoft]

_install is defined in a asm file :
[bits 32]

[global _install]
_install:
......


platform/object format? What's that?

[intel_breaker]

Platfrom: Windows/Linux/BSD, or anything else=)
Object format: elf, coff ?
Maybe you don't have to use underscore before function name, check it!

[SCSoft]

It's Ok after I add "section .text" to the asm file!

^^thanks all the same

[carbonBased]

Hopefully you understand *why*?

Most programmers tend to know what platform they're developing on! Keep in mind that other ABIs (Linux/ELF) will not use underscores and you'll get the same link error.

--Jeff

[SCSoft]

I think that the gcc will take the function to .text section but nasm won't.

where can I find the infomation for gcc and ld

[carbonBased]

You should be able to find information about it all over the internet. If you've got specific things you want to look into, google's probably your best resource. gcc.gnu.org probably contains a lot of information, as well.

ld is part of the binutils distribution, and has a homesite at http://www.gnu.org/software/binutils/

--Jeff