building module... errno undeclared

dbrazeau · 10-25-2011, 06:55 PM

I'm trying to build a driver module, but I keep getting:

Code:

error: 'errno' undeclared (first use in this function)

I'm including <linux/errno.h>, and it apparently has no problem finding it, so why is errno still undeclared?

NevemTeve · 10-25-2011, 10:20 PM

I think there is no errno when you are in the kernel space; return values between -4095 and -1 are the error codes.

dbrazeau · 10-26-2011, 11:39 AM

Quote:

Originally Posted by NevemTeve

I think there is no errno when you are in the kernel space; return values between -4095 and -1 are the error codes.

I believe you are correct. If you return an negative number, the kernel will internally set errno to that value.

NevemTeve · 10-26-2011, 12:08 PM

(When the supervisor call returns negative value, the C library sets the errno.)

dbrazeau · 10-27-2011, 11:23 AM

Quote:

Originally Posted by NevemTeve

(When the supervisor call returns negative value, the C library sets the errno.)

Oh, ok. Thanks.