[PATCH] Fix for using NFS root with if_arge

[Aleksandr Rybalko]

On Sat, 10 Mar 2012 14:54:39 -0800
Juli Mallett <jmallett at FreeBSD.org> wrote:

> On Sat, Mar 10, 2012 at 14:50, Juli Mallett <jmallett at freebsd.org>
> wrote:
> > On Sat, Mar 10, 2012 at 14:29, Aleksandr Rybalko <ray at ddteam.net>
> > wrote:
> >> On Sat, 10 Mar 2012 14:24:09 -0800
> >> Juli Mallett <jmallett at FreeBSD.org> wrote:
> >>> This patch seems to cause interrupt storms on rb450g's arge1
> >>> interface, at least if that interface is wired to the switch.  I
> >>> would guess it has to do with the MAC clock?
> >>
> >> Yeah, but not really this patch. This patch just workaround one
> >> problem which is unhide second. I'm still not sure what is real
> >> problem source, but think it is because clock for MAC output, or
> >> not run, or run on incorrect frequency.
> >
> > I guess I really don't understand the nature of the problem.  It
> > looks like this relates to moving the ring initialization out to
> > attach-time — why not just make the stop function do the right
> > thing and free allocated resources, instead of doing the latter in
> > detach?  Is it simply the lack of resetting the tx_prod, tx_cons,
> > tx_cnt and rx_cons fields in the init function if you move the ring
> > initialization to attach?  It looks to me like that could be the
> > problem.
> 
> Indeed, that's the issue.  If I modify your patch to instead be like
> below, no more interrupt storm:
> 
> 
> @@ -849,20 +860,17 @@
> 
>  	arge_stop(sc);
> 
> -	/* Init circular RX list. */
> -	if (arge_rx_ring_init(sc) != 0) {
> -		device_printf(sc->arge_dev,
> -		    "initialization failed: no memory for rx buffers
> \n");
> -		arge_stop(sc);
> -		return;
> -	}
> +	/*
> +	 * Reset ring consumer and producer values, etc.
> +	 */
> +	sc->arge_cdata.arge_rx_cons = 0;
> 
> -	/* Init tx descriptors. */
> -	arge_tx_ring_init(sc);
> +	sc->arge_cdata.arge_tx_prod = 0;
> +	sc->arge_cdata.arge_tx_cons = 0;
> +	sc->arge_cdata.arge_tx_cnt = 0;
> 
>  	arge_reset_dma(sc);
> 
> -
>  	if (sc->arge_miibus) {
>  		mii = device_get_softc(sc->arge_miibus);
>  		mii_mediachg(mii);

Cool!

I still not look into that so deeper :)
Thank you Juli!

Will test it with other zrouter guys, and then commit if you don't do
that faster :)

WBW

-- 
Aleksandr Rybalko <ray at ddteam.net>