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From: Eric Blake <eblake@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>, Amos Kong <akong@redhat.com>
Cc: qemu-devel@nongnu.org,
	Dmitry Krivenok <krivenok.dmitry@gmail.com>,
	Anthony Liguori <aliguori@amazon.com>
Subject: Re: [Qemu-devel] [PULL 4/4] net: disallow to specify multicast MAC address
Date: Fri, 18 Oct 2013 10:39:24 -0600	[thread overview]
Message-ID: <5261643C.70004@redhat.com> (raw)
In-Reply-To: <20131018163425.GA29516@stefanha-thinkpad.redhat.com>

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On 10/18/2013 10:34 AM, Stefan Hajnoczi wrote:

>>> +
>>> +bool net_macaddr_is_multicast(uint8_t *macaddr)
>>> +{
>>> +    return macaddr[0] % 2;
>>> +}
>>
>> Duplicate, we already have is_multicast_ether_addr() in include/net/eth.h
> 
> And net_macaddr_is_multicast() is wrong:
> bit 0 is the unicast/multicast bit, not bit 1.

Huh? 'foo % 2' is the same as 'foo & 1' - both check bit 0.  But I agree
that the '&' form is a bit easier to reason with, even if the compiler
is smart enough to use the same code for both.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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  reply	other threads:[~2013-10-18 16:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-18 13:35 [Qemu-devel] [PULL 0/4] Net patches Stefan Hajnoczi
2013-10-18 13:35 ` [Qemu-devel] [PULL 1/4] net: update nic info during device reset Stefan Hajnoczi
2013-10-18 13:35 ` [Qemu-devel] [PULL 2/4] net/e1000: update network information when macaddr is changed in guest Stefan Hajnoczi
2013-10-18 13:35 ` [Qemu-devel] [PULL 3/4] net/rtl8139: " Stefan Hajnoczi
2013-10-18 13:35 ` [Qemu-devel] [PULL 4/4] net: disallow to specify multicast MAC address Stefan Hajnoczi
2013-10-18 14:56   ` Amos Kong
2013-10-18 16:34     ` Stefan Hajnoczi
2013-10-18 16:39       ` Eric Blake [this message]
2013-10-18 16:41     ` Stefan Hajnoczi
2013-10-18 17:37       ` Dmitry Krivenok
2013-10-18 20:08     ` Dmitry Krivenok
2013-10-22  9:21       ` Amos Kong
2013-10-22  9:51         ` Dmitry Krivenok

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