Re: [Qemu-devel] [PATCH ] lan9118: fix multicast filtering

[Peter Maydell]

On 7 September 2012 15:56, Aurelien Jarno <address@hidden> wrote:
> On Thu, Aug 23, 2012 at 05:39:39PM +0200, Aurelien Jarno wrote:
>> The lan9118 emulation tries to compute the multicast index by calling
>> directly the crc32() function from zlib, but fails to get the correct
>> result.
>>
>> Use the common compute_mcast_idx() function instead, which gives the
>> correct result. This fixes IPv6 support.
>>
>> Signed-off-by: Aurelien Jarno <address@hidden>
>> ---
>>  hw/lan9118.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/lan9118.c b/hw/lan9118.c
>> index ff0a50b..ceaf96f 100644
>> --- a/hw/lan9118.c
>> +++ b/hw/lan9118.c
>> @@ -500,7 +500,7 @@ static int lan9118_filter(lan9118_state *s, const 
>> uint8_t *addr)
>>          }
>>      } else {
>>          /* Hash matching  */
>> -        hash = (crc32(~0, addr, 6) >> 26);
>> +        hash = compute_mcast_idx(addr);
>>          if (hash & 0x20) {
>>              return (s->mac_hashh >> (hash & 0x1f)) & 1;
>>          } else {
>
> Ping?
>
> For the record the Linux kernel uses the ether_crc() function for
> smsc911x.c, but also for 8139cp.c, 8139too.c and ethoc.c, which use
> compute_mcast_idx() on the QEMU side.

Looks ok to me. I did check the data sheet, which helpfully doesn't
say exactly what the CRC function is, and also the zlib docs (which
suggest we should use something that isn't what we were doing here).
So I guess

Reviewed-by: Peter Maydell <address@hidden>

Happy for you to commit directly or I can put it in arm-devs.next
if you prefer.

-- PMM