Won De Erick schrieb:
----- Original Message ----
From: Rink Springer <[EMAIL PROTECTED]>
On Mon, Dec 01, 2008 at 09:38:51AM +0100, Christoph Mallon wrote:
Userland is not allowed to write to ports. That's the bus error you see.
Also without a call to the exit syscall at the end, it will segfault.
Note that you can write to ports from userland by opening /dev/io - if
you have it opened, you can write to the ports.
I've added the following at the end
mov eax, 1 ; SYS_exit
call doint
doint:
int 0x80
ret
Besides, I can see the following at /dev
crw------- 1 root wheel 0, 16 Nov 27 01:53 io
How should I make this open? do i need to %include this?
You're probably better of writing this in C. Here is a wrapper for the
out instruction:
static inline outb(unsigned short port, unsigned char data)
{
asm("outb %0, %1" : : "a" (data), "dN" (port));
}
As Rink mentioned, you have to open /dev/io. The process must have
super-user privileges, see io(4).
Regards
Christoph
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