Linux kernel modifications for the Kernel Hacking exam
e3f685aa73
Jakub Kicinski says: ==================== ethtool: support FEC configuration over netlink This series adds support for the equivalents of ETHTOOL_GFECPARAM and ETHTOOL_SFECPARAM over netlink. As a reminder - this is an API which allows user to query current FEC mode, as well as set FEC manually if autoneg is disabled. It does not configure anything if autoneg is enabled (that said few/no drivers currently reject .set_fecparam calls while autoneg is disabled, hopefully FW will just ignore the settings). The existing functionality is mostly preserved in the new API. The ioctl interface uses a set of flags, and link modes to tell user which modes are supported. Here is how the flags translate to the new interface (skipping descriptions for actual FEC modes): ioctl flag | description | new API ================================================================ ETHTOOL_FEC_OFF | disabled (supported) | \ ETHTOOL_FEC_RS | | ` link mode bitset ETHTOOL_FEC_BASER | | / .._A_FEC_MODES ETHTOOL_FEC_LLRS | | / ETHTOOL_FEC_AUTO | pick based on cable | bool .._A_FEC_AUTO ETHTOOL_FEC_NONE | not supported | no bit, no AUTO reported Since link modes are already depended on (although somewhat implicitly) for expressing supported modes - the new interface uses them for the manual configuration, as well as uses link mode bit number to communicate the active mode. Use of link modes allows us to define any number of FEC modes we want, and reuse the strset we already have defined. Separating AUTO as its own attribute is the biggest changed compared to the ioctl. It means drivers can no longer report AUTO as the active FEC mode because there is no link mode for AUTO. active_fec == AUTO makes little sense in the first place IMHO, active_fec should be the actual mode, so hopefully this is fine. The other minor departure is that None is no longer explicitly expressed in the API. But drivers are reasonable in handling of this somewhat pointless bit, so I'm not expecting any issues there. One extension which could be considered would be moving active FEC to ETHTOOL_MSG_LINKMODE_*, but then why not move all of FEC into link modes? I don't know where to draw the line. netdevsim support and a simple self test are included. Next step is adding stats similar to the ones added for pause. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> , |
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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.