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We're currently sending non-blocking H2G messages using the EVENT type, which suppresses all CTB protocol replies from the GuC, including the failure cases. This might cause errors to slip through and manifest as unexpected behavior (e.g. a context state might not be what the driver thinks it is because the state change command was silently rejected by the GuC). To avoid this kind of problems, we can use the FAST_REQUEST type instead, which suppresses the reply only on success; this way we still get the advantage of not having to wait for an ack from the GuC (i.e. the H2G is still non-blocking) while still detecting errors. Since we can't escalate to the caller when a non-blocking message fails, we need to escalate to GT reset instead. Note that FAST_REQUEST failures are NOT expected and are usually a sign that the H2G was either malformed or requested an illegal operation. v2: assign fence values to FAST_REQUEST messages, fix abi doc, use xe_gt printers (Michal). v3: fix doc alignment, fix and improve prints (Michal) Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> Cc: John Harrison <John.C.Harrison@Intel.com> Cc: Matthew Brost <matthew.brost@intel.com> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com> Reviewed-by: Matthew Brost <matthew.brost@intel.com> #v2 Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.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 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.