The TAP device only lasts as long as the DPDK application that opened
it is running. This behavior is bad if the DPDK application needs
to be updated transparently without disturbing other services
using the tap device.
Add a persist feature to the TAP device. If this flag is set, the
kernel network device remains even if after the application has exited.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>