Nope. You're setting the bit from 0 to ((8*64)-1), where bit 0 starts
at mc_filter offset zero.
Really, it looks to me like only bytes 0, 1 are getting set.
mc_filter[2-63] remain untouched. (?)
Re: endinaness, I think big endian is OK. The byte[1]<<8 + byte[0]
should be the same as (u16)&byte[1].
Thanks,
Nat
On Mon, 2002-12-02 at 16:55, Jeff Garzik wrote:
> Nat Ersoz wrote:
> > Fellows,
> >
> > I'm debugging a problem in the natsemi.c driver which has the symptom
> > that muticast reception quits for no apparent reason. Unicast still
> > works fine, the multicast stream is being sent, but no packets make it
> > past the hash filter. In versions of the driver, 2.4.19 and before, we
> > "fixed" this problem by setting ifconfig "allmuti" on the device.
> >
> > As I'm writing a debug routine, I notice that:
> >
> >
> > static void __set_rx_mode(struct net_device *dev)
> > {
> > ...
> >
> > for (i = 0, mclist = dev->mc_list;
> > mclist && i < dev->mc_count;
> > i++, mclist = mclist->next) {
> > set_bit_le(
> > dp83815_crc(ETH_ALEN, mclist->dmi_addr) & 0x1ff,
> > mc_filter); /* WHOOPS!! Shouldn't this be &mc_filter[i*2]
> > ?? */
> > }
> > ...
> > }
> >
> > (see the comment containnig WHOOPS)
>
>
> Nope. You're setting the bit from 0 to ((8*64)-1), where bit 0 starts
> at mc_filter offset zero. So, setting bit 400 via this code is just fine.
>
> Perfectly legal to do since you know your boundaries, but a bit scary to
> be intentionally overrunning the bounds of an unsigned long :) Also I
> _think_ in 2.5.x kernels this slips into the category of abuse, since
> the compiler started warning about the use of set_bit on things that
> were not strictly unsigned long.
>
> I am, however, a bit curious why this code differs from Becker's
> natsemi.c in the use of set_bit versus set_bit_le. writel() and outl()
> do byte-swapping for us, so I wonder if this code is correct on big-endian.
>
> Jeff
>
>
--
_________________________________________
Nat Ersoz nat.ersoz@myrio.com -o)
Myrio Corporation Phone: 425.897.7278 /\\
3500 Carillon Point Cell: 425.417.5182 _\_V
Kirkland, WA 98033 Fax: 425.897.5600
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