From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC virt-spec PATCH] only writing out the last byte of MAC makes it have effect Date: Thu, 21 Mar 2013 12:53:33 +0200 Message-ID: <20130321105333.GC30874@redhat.com> References: <1363834956-9409-1-git-send-email-akong@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1363834956-9409-1-git-send-email-akong@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Amos Kong Cc: qemu-devel@nongnu.org, stefanha@redhat.com, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Thu, Mar 21, 2013 at 11:02:36AM +0800, Amos Kong wrote: > The lengcy guests don't have mac programming command, we don't know when > it's safe to use MAC. We can change QEMU to make MAC change effect when > the last byte of MAC is written to config space. > > Signed-off-by: Amos Kong > --- > virtio-spec.lyx | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/virtio-spec.lyx b/virtio-spec.lyx > index dbc4ef0..bb289fb 100644 > --- a/virtio-spec.lyx > +++ b/virtio-spec.lyx > @@ -5430,7 +5430,7 @@ T_CTRL_MAC_TABLE_SET. > > \begin_layout Standard > > -\change_inserted -1930653948 1358506710 > +\change_inserted -1930653948 1363832689 > The config space > \begin_inset Quotes eld > \end_inset > @@ -5464,6 +5464,15 @@ mac > Therefore, VIRTIO_NET_CTRL_MAC_ADDR_SET is preferred, especially while > the NIC is up. > The command-specific-data is a 6-byte MAC address. > +\end_layout > + > +\begin_layout Standard > + > +\change_inserted -1930653948 1363833477 > +The legacy guests don't support the new command, they still change MAC address > + in original way, that's not atomic. > + For more robust, QEMU only makes the MAC change effect when the last byte > + of MAC address is written to config space. > \change_unchanged > > \end_layout The wording can be improved, but before that - Rusty, what do you think about such a hack? Worth supporting or let's just ask everyone to update drivers? > -- > 1.8.1.4