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The current context uAPI allows for two methods of setting context parameters: SET_CONTEXT_PARAM and CONTEXT_CREATE_EXT_SETPARAM. The former is allowed to be called at any time while the later happens as part of GEM_CONTEXT_CREATE. Currently, everything settable via one is settable via the other. While some params are fairly simple and setting them on a live context is harmless such the context priority, others are far trickier such as the VM or the set of engines. In order to swap out the VM, for instance, we have to delay until all current in-flight work is complete, swap in the new VM, and then continue. This leads to a plethora of potential race conditions we'd really rather avoid. Unfortunately, both methods of setting the VM and the engine set are in active use today so we can't simply disallow setting the VM or engine set vial SET_CONTEXT_PARAM. In order to work around this wart, this commit adds a proto-context struct which contains all the context create parameters. v2 (Daniel Vetter): - Better commit message - Use __set/clear_bit instead of set/clear_bit because there's no race and we don't need the atomics v3 (Daniel Vetter): - Use manual bitops and BIT() instead of __set_bit v4 (Daniel Vetter): - Add a changelog to the commit message - Better hyperlinking in docs - Create the default PPGTT in i915_gem_create_context v5 (Daniel Vetter): - Hand-roll the initialization of UCONTEXT_PERSISTENCE Signed-off-by: Jason Ekstrand <jason@jlekstrand.net> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210708154835.528166-17-jason@jlekstrand.net
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.