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For DEVICE_VERSION_V2, the hardware only supports max two layer VLAN tags, including port based tag inserted by hardware, tag in tx buffer descriptor(get from skb->tci) and tag in packet. For transmit packet: If port based VLAN disabled, and vf driver gets a VLAN tag from skb, the VLAN tag must be filled to the Outer_VLAN_TAG field (tag near to DMAC) of tx buffer descriptor, otherwise it may be inserted after the tag in packet. If port based VLAN enabled, and vf driver gets a VLAN tag from skb, the VLAN tag must be filled to the VLAN_TAG field (tag far to DMAC) of tx buffer descriptor, otherwise it may be conflicted with port based VLAN, and raise a hardware error. For receive packet: The hardware will strip the VLAN tags and fill them in the rx buffer descriptor, no matter port based VLAN enable or not. Because port based VLAN tag is useless for stack, so vf driver needs to discard the port based VLAN tag get from rx buffer descriptor when port based VLAN enabled. So vf must know about the port based VLAN state. For DEVICE_VERSION_V3, the hardware provides some new configuration to improve it. For transmit packet: When enable tag shift mode, hardware will handle the VLAN tag in outer_VLAN_TAG field as VLAN_TAG, so it won't conflict with port based VLAN. And hardware also make sure the tag before the tag in packet. So vf driver doesn't need to specify the tag position according to the port based VLAN state anymore. For receive packet: When enable discard mode, hardware will strip and discard the port based VLAN tag, so vf driver doesn't need to identify it from rx buffer descriptor. So modify the port based VLAN configuration, simplify the process for vf handling the VLAN tag. Signed-off-by: Guojia Liao <liaoguojia@huawei.com> Signed-off-by: Huazhong Tan <tanhuazhong@huawei.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 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.