[dpdk-users] Running DPDK as non-root

Jez Higgins jez at jezuk.co.uk
Thu Jul 7 17:47:27 CEST 2016


Is it possible to run applications that use DPDK on Linux as anything
other than root?  I think the answer is no, but I wonder if anyone has
worked it out.

5.2 of the getting started guide says

  with a number of small permission adjustments it is possible to run
these applications as a user other than “root”

but this seems insufficient.  I have changed the permissions on the
hugepages mountpoint (in my case /dev/hugepages), on /dev/uio0, on
/sys/class/uio/uio0/device/config, and on

Making these changes is sufficient initialise the application.  However,
a non-root user does not seem to be able to read /proc/self/pagemap.
More specifically, a non-root user can open and read /proc/self/pagemap,
but only ever reads zeros.  This means the mapping the hugepages virtual
to physical addresses isn't correct, and so actually allocating even
reasonably small amounts of memory (for example the log buffer) is
liable to fail.

Apparently, access to /proc/self/pagemap is controlled by the
CAP_SYS_ADMIN capability.  However, if I use setcap to enable that
capability, I can't even open it, never mind read it.

I bodged around this by setting my default hugepage size to 1GB, rather
than 2MB.  The virtual to physical mapping is still wrong, but I can at
least get DPDK to initialise.  I doubt it's correct though.

At that point, if I try to initialise a port with rte_eth_dev_start it
fails.  I'm running in a vm, so using the vmxnet3 driver.  It's failing
to activate the device down in vmxnet3_dev_start.

If I run as root, however, everything fires up and runs correctly.

Is it possible to get DPDK up and running as non-root - if so, can
anyone guide me to what I'm missing? Or should I be giving this up as a
bad job?

Thanks in advance,

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