Date: Mon, 01 Dec 2008 10:35:16 +0100 From: Christoph Mallon <christoph.mallon@gmx.de> To: Won De Erick <won.derick@yahoo.com> Cc: freebsd-hackers@freebsd.org, Rink Springer <rink@FreeBSD.org>, freebsd-hardware@freebsd.org Subject: Re: Watchdog for Boser (HS-7001) Message-ID: <4933AFD4.3070501@gmx.de> In-Reply-To: <611173.7111.qm@web45805.mail.sp1.yahoo.com> References: <547602.79284.qm@web45809.mail.sp1.yahoo.com> <4933A29B.8060907@gmx.de> <20081201090421.GA99082@rink.nu> <611173.7111.qm@web45805.mail.sp1.yahoo.com>
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Won De Erick schrieb:
>> ----- Original Message ----
>
>> From: Rink Springer <rink@FreeBSD.org>
>>
>>
> 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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