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CAN XL data frames contain an 8-bit virtual CAN network identifier (VCID). A VCID value of zero represents an 'untagged' CAN XL frame. To receive and send these optional VCIDs via CAN_RAW sockets a new socket option CAN_RAW_XL_VCID_OPTS is introduced to define/access VCID content: - tx: set the outgoing VCID value by the kernel (one fixed 8-bit value) - tx: pass through VCID values from the user space (e.g. for traffic replay) - rx: apply VCID receive filter (value/mask) to be passed to the user space With the 'tx pass through' option CAN_RAW_XL_VCID_TX_PASS all valid VCID values can be sent, e.g. to replay full qualified CAN XL traffic. The VCID value provided for the CAN_RAW_XL_VCID_TX_SET option will override the VCID value in the struct canxl_frame.prio defined for CAN_RAW_XL_VCID_TX_PASS when both flags are set. With a rx_vcid_mask of zero all possible VCID values (0x00 - 0xFF) are passed to the user space when the CAN_RAW_XL_VCID_RX_FILTER flag is set. Without this flag only untagged CAN XL frames (VCID = 0x00) are delivered to the user space (default). The 8-bit VCID is stored inside the CAN XL prio element (only in CAN XL frames!) to not interfere with other CAN content or the CAN filters provided by the CAN_RAW sockets and kernel infrastruture. Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Link: https://lore.kernel.org/all/20240212213550.18516-1-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
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.