# lsb_release -rd
Description: Ubuntu 12.04.1 LTS
Release: 12.04
# ibv_devinfo -v
libibverbs: Warning: no userspace device-specific driver found for /sys/class/infiniband_verbs/uverbs0
No IB devices found
# strace -f ibv_devinfo -v |& tail -n 12
open("/sys/class/infiniband_verbs/uverbs0/device/vendor", O_RDONLY) = 3
read(3, "0x15b3\n", 8) = 7
close(3) = 0
open("/sys/class/infiniband_verbs/uverbs0/device/device", O_RDONLY) = 3
read(3, "0x1003\n", 8) = 7
close(3) = 0
write(2, "libibverbs: Warning: no userspac"..., 103libibverbs: Warning: no userspace device-specific driver found for /sys/class/infiniband_verbs/uverbs0
) = 103
futex(0x7f4d12de31d0, FUTEX_WAKE_PRIVATE, 2147483647) = 0
write(2, "No IB devices found\n", 20No IB devices found
) = 20
exit_group(-1) = ?
See also http://git.kernel.org/?p=libs/infiniband/libmlx4.git;a=commitdiff;h=1488631df283f03aefb1a7f67367c6e4e371a9a3
And the fix is to update to a new libmlx4 version, which is already in 12.10 / Quantal. I'm not sure if there's anything that can be done in the context of continuing maintenance to 12.04.