mirror of https://gitee.com/openkylin/linux.git
5b64347930
We introduced the virtchnl interface in order to have an interface for talking to a virtual device driver which was host-driver agnostic. This interface has its own definitions, including one for link speed. The host driver has to talk to the virtchnl interface using these new definitions in order to remain compatible. Today, the i40e link_speed enumerations are value-exact matches for the virtchnl interface, so it was originally decided to simply use a typecast. However, this is unsafe, and makes it easier for future drivers to continue this unsafe practice. There is nothing guaranteeing these values are exact, and the type-cast would hide any compiler warning which indicates the problem. Rather than rely on this type cast, introduce a helper function which can convert the AdminQ link speed definition into a virtchnl definition. This can then be used by host driver implementations in order to safely convert to the interface recognized by the virtual functions. If the link speed is not able to be represented by the virtchnl definitions we'll report UNKNOWN which is the safest result. This will ensure that should the driver specific link_speeds actual bit definitions change, we do not report them incorrectly according to the VF. Additionally, this provides a better pattern for future drivers to copy, as it is more likely a future device may not use the exact same bit-wise definition as the current virtchnl interface. Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Tested-by: Andrew Bowers <andrewx.bowers@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.