This is on yocto-linux 4.19.87 on X86_64. DPDK (stable) 18.11.11
I am working on a project where I am trying to make use of the 'virtio-user'
exception path and it (sort of) seems to be working. The issue I am trying to
understand is the following:
Background -
Per the how-to documentation
(https://doc.dpdk.org/guides-25.07/howto/virtio_user_as_exception_path.html), I
have called rte_eal_init() passing in the PCI address of my physical interfaces.
I am also creating a couple of these "exception" interfaces with the following
code -
char portname[32], portargs[256];
char macaddr[6] = { 0x00, 0x0c, 0x1b, 0x29, 0x29, 0x71 };
uint16_t portid;
/**
* Create the first 'iflan0'
*/
snprintf(portargs, 256,
"path=/dev/vhost-net,queues=2,queue_size=1024,iface=iflan0,mac=%02x:%02x:%02x:%02x:%02x:%02x",
macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4], macaddr[5]);
/**
* Call the hotplug layer
*/
if (rte_eal_hotplug_add("vdev", "virt-user0", portargs) < 0) {
fprintf(stderr, "[DPDK::hotplug] failed to create iflan0
(virtio-user0)\n");
return -1;
}
/**
* Create the second 'ifwan0'
*/
macaddr[5]++;
snprintf(portargs, 256,
"path=/dev/vhost-net,queues=2,queue_size=1024,iface=ifwan0,mac=%02x:%02x:%02x:%02x:%02x:%02x",
macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4], macaddr[5]);
/**
* Call the hotplug layer
*/
if (rte_eal_hotplug_add("vdev", "virt-user1", portargs) < 0) {
fprintf(stderr, "[DPDK::hotplug] failed to create iflan0
(virtio-user0)\n");
return -1;
}
...
RTE_ETH_FOREACH_DEV(portid) {
if (port_init(portid, bufPool, NRXQUEUES, NTXQUEUES) < 0) {
fprintf(stderr, "[DPDK::port_init] failed to init DPDK port %u",
portid);
return -1;
}
}
...
/* Retrieve the ifindex of iflan0 and ifwan0 */
unsigned int iflan0_index = if_nametoindex("iflan0");
unsigned int ifwan0_index = if_nametoindex("ifwan0");
fprintf(stdout, "[DPDK] Exception interface 'iflan0': %u", iflan0_index);
fprintf(stdout, "[DPDK] Exception interface 'ifwan0': %u", ifwan0_index);
... /* onto the packet processing loops */
The interfaces are instantiated and those two logs messages are seen -
. . .
[DPDK] Exception interface 'iflan0': 58
[DPDK] Exception interface 'ifwan0': 59
. . .
However, when I check the list of kernel interfaces using 'ip link show', I
find:
pmahan-dpdk-v1: # ip link show
. . .
66: iflan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT
group default qlen 1000
link/ether 00:0c:1b:29:29:71 brd ff:ff:ff:ff:ff:ff
67: ifwan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT
group default qlen 1000
link/ether 00:0c:1b:29:29:72 brd ff:ff:ff:ff:ff:ff
So, some point after I created and started these ports and obtain the original
ifindexes, they were deleted and re-created. I have some clue from the IKE
kernel log messages:
...
Sep 27 23:30:22 2025 pmahan-dpdk-v1 IKE: 11[KNL] interface iflan0 activated
Sep 27 23:30:22 2025 pmahan-dpdk-v1 IKE: 09[KNL] interface ifwan0 activated
...
Sep 27 23:30:22 2025 pmahan-dpdk-v1 IKE: 09[KNL] interface iflan0 deactivated
Sep 27 23:30:22 2025 pmahan-dpdk-v1 IKE: 13[KNL] interface iflan0 deleted
Sep 27 23:30:22 2025 pmahan-dpdk-v1 IKE: 12[KNL] interface ifwan0 deactivated
Sep 27 23:30:22 2025 pmahan-dpdk-v1 IKE: 05[KNL] interface ifwan0 deleted
I never see another IKE log about those interfaces being activated again
(possibly because they show as DOWN).
Short of crawling through the guts of the virtio-user support in vdev, I thought
I would start asking questions here.
Also, is there any specific logging I can enabled to see if I can understand why
this is happening?
Thanks for any help,
Patrick
