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Debugging certain flows in the offloaded switch data path can be done by installing two tc-mirred filters for mirroring: one in the hardware data path, which copies the frames to the CPU, and one which takes the frame from there and mirrors it to a virtual interface like a dummy device, where it can be seen with tcpdump. The effect of having 2 filters run on the same packet can be obtained by default using tc, by not specifying either the 'skip_sw' or 'skip_hw' keywords. Instead of refusing to offload mirroring/redirecting packets towards interfaces that aren't switch ports, just treat every other destination for what it is: something that is handled in software, behind the CPU port. Usage: $ ip link add dummy0 type dummy; ip link set dummy0 up $ tc qdisc add dev swp0 clsact $ tc filter add dev swp0 ingress protocol ip flower action mirred ingress mirror dev dummy0 Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Link: https://patch.msgid.link/20241023135251.1752488-7-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.