The generated fixed MAC address stored the interface index in a single byte, which wraps after 256 devices and produces duplicate MACs under repeated hot-plug. Spread the index across the last two bytes of the address, extending the unique range to 65536.
Signed-off-by: Stephen Hemminger <[email protected]> --- drivers/net/tap/rte_eth_tap.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c index 31c8c185e9..fcc452527b 100644 --- a/drivers/net/tap/rte_eth_tap.c +++ b/drivers/net/tap/rte_eth_tap.c @@ -2276,13 +2276,13 @@ set_mac_type(const char *key __rte_unused, return 0; if (!strncasecmp(ETH_TAP_MAC_FIXED, value, strlen(ETH_TAP_MAC_FIXED))) { - static int iface_idx; + static uint16_t iface_idx; /* fixed mac = 02:64:74:61:70:<iface_idx> */ - memcpy((char *)user_mac->addr_bytes, "\002dtap", - RTE_ETHER_ADDR_LEN); - user_mac->addr_bytes[RTE_ETHER_ADDR_LEN - 1] = - iface_idx++ + '0'; + memcpy((char *)user_mac->addr_bytes, "\002dtap", RTE_ETHER_ADDR_LEN); + user_mac->addr_bytes[4] = iface_idx >> 8; + user_mac->addr_bytes[5] = (uint8_t)iface_idx; + ++iface_idx; goto success; } -- 2.51.0
