[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [RFC v3 5/6] xen-netback: use a random MAC address and force bridge root block
From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx> The purpose of using a static MAC address of FE:FF:FF:FF:FF:FF was to prevent our backend interfaces from being used by the bridge and nominating our interface as a root port on the bridge. This was possible given that the bridge code will use the lowest MAC address for a port once a new interface gets added to the bridge. Sticking to a static MAC address is undesirable for a few reasons: a) using a static MAC address by default on all interfaces can lead to possible conflicts with IPv6 SLAAC and DAD b) The bridge code has a generic bridge port 'root block' feature to allow interfaces to opt out from root bridge port nominations. We want to help stop spreading the use of a high MAC address as a hack to do root port block, and instead get folks to use the proper APIs for this. This modifies xen-netback to use a random MAC address with the xen OUI prefix and enables the bridge root block feature since initialization. Although toggling the root block feature requires the iproute2 bridge tool [0] or sysfs [1] xen-netback users would only need to toggle this off in the case that the net_device is required to be a candidate for root port nomination on the bridge. This is an acceptable compromise in order to avoid the possible conflicts with IPv6 SLAAC and DAD. [0] bridge link set dev vif2.0 root_block off [1] echo 1 > /sys/devices/vif-2-0/net/vif2.0/brport/root_block Cc: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> Cc: bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx Cc: kvm@xxxxxxxxxxxxxxx Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx> --- drivers/net/xen-netback/interface.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 7669d49..79d71ec 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -42,6 +42,8 @@ #define XENVIF_QUEUE_LENGTH 32 #define XENVIF_NAPI_WEIGHT 64 +static const u8 xen_oui[3] = { 0x00, 0x16, 0x3e }; + int xenvif_schedulable(struct xenvif *vif) { return netif_running(vif->dev) && netif_carrier_ok(vif->dev); @@ -346,15 +348,9 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, for (i = 0; i < MAX_PENDING_REQS; i++) vif->mmap_pages[i] = NULL; - /* - * Initialise a dummy MAC address. We choose the numerically - * largest non-broadcast address to prevent the address getting - * stolen by an Ethernet bridge for STP purposes. - * (FE:FF:FF:FF:FF:FF) - */ - memset(dev->dev_addr, 0xFF, ETH_ALEN); - dev->dev_addr[0] &= ~0x01; - + eth_hw_addr_random(dev); + memcpy(dev->dev_addr, xen_oui, 3); + dev->priv_flags |= IFF_BRIDGE_ROOT_BLOCK; netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT); netif_carrier_off(dev); -- 1.9.0 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |