some question about kernel-2.4.20/lib/errno.c

[ao_yuan_young]

In kernel-2.4.20, there was a file named errno.c in folder lib. And a global variable named errno was defined in this .c file. But in kernel-2.6.27, this file doesn't exist any more.
In my hand, there are some code based on kernel-2.4.20, and the global variable errno is used, so if compile the code in my hand based on kernel-2.6.27, an error is given: no definition of errno. How do I solve this problem?

*ps: I'm coding in kernel space.

[Rubberman]

In the 2.6 kernel code I have, there is an extern int errno declared in linux/unistd.h. My guess is that if you declare an external int to that variable, you should be ok.

[ao_yuan_young]

I don't think it would work to do like that, for in kernel-2.6.27, there is no definition of errno in linux/unistd.h. All the file where variable errno appears are in folder arch.

[Rubberman]

I don't think it would work to do like that, for in kernel-2.6.27, there is no definition of errno in linux/unistd.h. All the file where variable errno appears are in folder arch.

Well, there was in 2.6.18 kernels. Have you tried just declaring an extern int errno; in your code? It could be defined in the assembly language modules somewhere.