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The canonical definition for all the link modes is in linux/ethtool.h, which is complemented by the link_mode_params array stored in net/ethtool/common.h . That array contains all the metadata about each of these modes, including the Speed and Duplex information. Phylib and phylink needs that information as well for internal management of the link, which was done by duplicating that information in locally-stored arrays and lookup functions. This makes it easy for developpers adding new modes to forget modifying phylib and phylink accordingly. However, the link_mode_params array in net/ethtool/common.c is fairly inefficient to search through, as it isn't sorted in any manner. Phylib and phylink perform a lot of lookup operations, mostly to filter modes by speed and/or duplex. We therefore introduce the link_caps private array in phy_caps.c, that indexes linkmodes in a more efficient manner. Each element associated a tuple <speed, duplex> to a bitfield of all the linkmodes runs at these speed/duplex. We end-up with an array that's fairly short, easily addressable and that it optimised for the typical use-cases of phylib/phylink. That array is initialized at the same time as phylib. As the link_mode_params array is part of the net stack, which phylink depends on, it should always be accessible from phylib. Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Link: https://patch.msgid.link/20250307173611.129125-3-maxime.chevallier@bootlin.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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.