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It is required that the caller declare the exact number of dwords they wish to write into the ring. This is required for two reasons, we need to allocate sufficient space for the entire command packet and we need to be sure that the contents are completely written to avoid executing stale data. The current interface requires for any bug to be caught in review, the reader has to carefully count the number of intel_ring_emit() between intel_ring_begin() and intel_ring_advance(). If we record the end of the packet of each intel_ring_begin() we can also have CI check for us. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170206170502.30944-1-chris@chris-wilson.co.uk
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.