[ECOS] Re: What does "implements CYGINT_IO_ETH_MULTICAST" mean?

Grant Edwards grant.b.edwards@gmail.com
Fri Sep 24 19:22:00 GMT 2010


On 2010-09-24, Jay Foster <jay@systech.com> wrote:

>   I have an ethernet driver that does implement these, but I don't
> actually use it.  Generally, what your driver needs to do is setup the 
> CAM registers and modes appropriately.

Thanks -- my driver does implement SET_MC_LIST and SET_MC_ALL, so I
wasn't asking how to implement them.

I was asking what is required of an Ethernet driver that asserts
CYGINT_IO_ETH_MULTICAST.  My _guess_ was that CYGINT_IO_ETH_MULTICAST
implied implementation of SET_MC_LIST and SET_MC_ALL.  But, I couldn't
find that documented anywhere, and one extant driver I looked at
(ppc405) appears to contractict my initial guess.

NB: Since you're not actually using multicast it doesn't really
    matter, but you might want to check the length of the address list
    being passed to MC_LIST.  The CAM only has room for a total of 21
    addresses, so if the list is longer than 20, a good workaround is
    to to discard the list and just set the GROUP_ACC bit in CAMCON.
    IOW, treat MC_LIST w/ >20 addresses as if it were MC_ALL.

-- 
Grant Edwards               grant.b.edwards        Yow! My NOSE is NUMB!
                                  at               
                              gmail.com            


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