Bug ID 1922501: TMM crash loop due to missing kernel driver

Last Modified: Jun 28, 2025

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
17.5.0

Fixed In:
17.5.1

Opened: Apr 09, 2025

Severity: 3-Major

Symptoms

TMM goes into a crash loop with following logs in 'tmm' logs notice EAL: Driver cannot attach the device (<VMBus-ID>) notice EAL: Failed to attach device on primary process notice dpdk[<VMBus-ID>]: Error: rte_dev_probe failed: err=-95 notice xnet_lib [vmbus:eth2]: Error: Failed to initialize driver notice xnet[00:e2.0]: Error: Unable to attach to xnet dev This is due to missing uio_hv_generic kernel module which gets removed on TMM shutdown but fails to be re-inserted upon TMM post-crash restart.

Impact

Traffic disrupted while tmm restarts.

Conditions

1) BIG-IP on HyperV or Azure 2) Using xnet-DPDK driver 3) TMM crashes due to any other reason and restarts; can not repro directly using 'bigstart restart tmm' unless a 'bigstart restart' also reproduces the initial crash as well

Workaround

(A) 1) Add 'modprobe uio_hv_generic' to '/usr/lib/bigstart/functions' This will likely require remounting /usr to allow writing; this can be done via sudo mount -o remount,rw /usr 2) Within 'functions', search for 'vadc_restore_vmbus_nics()' and add 'modprobe uio_hv_generic' to bottom of function after 'done' 3) Afterwards, restart TMM with 'bigstart restart tmm' (B) 1) Switch to 'sock' driver by adding following config [root@BIGIP:Active:Standalone] config # cat /config/tmm_init.tcl device driver vendor_dev f5f5:f550 sock [root@BIGIP:Active:Standalone] config # 2) Restart TMM with 'bigstart restart tmm'

Fix Information

Re-activate missing module after TMM crash

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips