debugging network device driver

Pyun YongHyeon pyunyh at
Sun Feb 22 17:20:13 PST 2009

On Sun, Feb 22, 2009 at 09:00:29AM +0100, Tesch Zoltan wrote:
> Hi,
> I have just tried to port SiS190 Linux driver to FreebBSD. It seems to
> me that this driver looks like r8169 and for this reason my port is
> based on the "re" device driver of FreeBSD 6.4.

Hmm, I have no idea why SiS190 is similar to RTL8169. Both
controllers have small set of registers though.

> I can load the module, attach to SiS190 device, miibus and phy but when
> I try to set up the interface with ifconfig (ifconfig sis0 up) the
> computer freezes. I have tried to print status information from my
> driver (using printf`s in the code) but the last record in the log is
> that miibus_readreg returned a good value, no other record is logged
> into the system log.

It's hard to say what was wrong here. Datasheet is not available
to open source developers and the controller seem to have severe
alignment restrictions as well as lack of auto-padding.

> My questions:
> Is there any way to switch to kernel debug mode in this situation to see
> what happened or is it possible to run  the module under the supervision
> of kernel debugger running on the machine, because this laptop has no
> serial line or any other network interface.

ktr(4) is much better than printfs. Btw there was a post for
SiS190 driver so you can reference his work.

Having a wired/wireless USB network controller would make your
life easier.

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