ac02a451a6
sja1105 uses dsa_8021q for DSA tagging, a format which is VLAN at heart and which is compatible with cascading. A complete description of this tagging format is in net/dsa/tag_8021q.c, but a quick summary is that each external-facing port tags incoming frames with a unique pvid, and this special VLAN is transmitted as tagged towards the inside of the system, and as untagged towards the exterior. The tag encodes the switch id and the source port index. This means that cross-chip bridging for dsa_8021q only entails adding the dsa_8021q pvids of one switch to the RX filter of the other switches. Everything else falls naturally into place, as long as the bottom-end of ports (the leaves in the tree) is comprised exclusively of dsa_8021q-compatible (i.e. sja1105 switches). Otherwise, there would be a chance that a front-panel switch transmits a packet tagged with a dsa_8021q header, header which it wouldn't be able to remove, and which would hence "leak" out. The only use case I tested (due to lack of board availability) was when the sja1105 switches are part of disjoint trees (however, this doesn't change the fact that multiple sja1105 switches still need unique switch identifiers in such a system). But in principle, even "true" single-tree setups (with DSA links) should work just as fine, except for a small change which I can't test: dsa_towards_port should be used instead of dsa_upstream_port (I made the assumption that the routing port that any sja1105 should use towards its neighbours is the CPU port. That might not hold true in other setups). Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
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| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| .gitignore | ||
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| README | ||
README
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 Restructured Text 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.