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Signed-off-by: Simon Perretta <simon.perretta@imgtec.com> Reviewed-by: Frank Binns <frank.binns@imgtec.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39453>
139 lines
5.8 KiB
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139 lines
5.8 KiB
ReStructuredText
PowerVR
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=======
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PowerVR is an open source Vulkan driver for Imagination Technologies PowerVR
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GPUs, starting with those based on the Rogue architecture.
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The driver is conformant to Vulkan 1.0 on `BXS-4-64 <https://www.khronos.org/conformance/adopters/conformant-products#submission_936>`__,
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but **not yet on other GPUs and Vulkan versions**, so it requires exporting
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``PVR_I_WANT_A_BROKEN_VULKAN_DRIVER=1`` to the environment for GPUs that aren't
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conformant to any Vulkan version before running any Vulkan content.
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The following hardware is currently in active development:
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========= =========== ============== =======
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Product Series B.V.N.C Vulkan
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========= =========== ============== =======
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AXE-1-16M A-Series 33.15.11.3 1.2
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BXM-4-64 B-Series 36.52.104.182 1.2
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BXM-4-64 B-Series 36.56.104.183 1.2
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BXS-4-64 B-Series 36.53.104.796 1.2
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========= =========== ============== =======
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The following hardware is partially supported and not currently
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under active development:
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========= =========== ============== =======
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Product Series B.V.N.C Vulkan
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========= =========== ============== =======
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GX6250 Series 6XT 4.40.2.51 1.2
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========= =========== ============== =======
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Various core-specific features and workarounds are likely to be unimplemented
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for this hardware. Some very simple Vulkan applications may run unhindered, but
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instability and corruption are to be expected until additional feature support
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and workarounds are in place.
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The following hardware is unsupported and not under active development:
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========= =========== ==============
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Product Series B.V.N.C
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========= =========== ==============
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G6110 Series 6XE 5.9.1.46
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GX6250 Series 6XT 4.45.2.58
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GX6650 Series 6XT 4.46.6.62
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GE7800 Series 7XE 15.5.1.64
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GE8300 Series 8XE 22.67.54.30
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GE8300 Series 8XE 22.68.54.30
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GE8300 Series 8XE 22.102.54.38
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BXE-2-32 B-Series 36.29.52.182
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BXE-4-32 B-Series 36.50.54.182
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========= =========== ==============
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Device info and firmware_ have been made available for these devices, typically
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due to community requests or interest, but no support is guaranteed beyond this.
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.. _firmware: https://gitlab.freedesktop.org/imagination/linux-firmware
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In some cases, a product name is shared across multiple BVNCs so to check for
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support make sure the BVNC matches the one listed. As the feature set and
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hardware issues can vary between BVNCs, additional driver changes might be
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necessary even for devices sharing the same product name.
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Hardware documentation can be found at: https://docs.imgtec.com/
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Note: GPUs prior to Series6 do not have the hardware capabilities required to
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support Vulkan and therefore cannot be supported by this driver.
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Multi-Architecture support
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--------------------------
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To support multiple distinct hardware generations without too much
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spaghetti-code, the PowerVR build compiles a few files multiple times (once
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per hardware architecture) and uses a system of macros and aliases to be
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able to refer to the different versions.
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The files that get compiled multiple times are those named
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:file:`pvr_arch_*.c`. These files contain definitions of functions prefixed
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with ``pvr_arch_`` (instead of the normal ``pvr_``-prefix). The ``arch``-bit
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of that function is a placeholder, which gets replaced at compile-time, thanks
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to a system of defines in the corresponding header file, supported by a set
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of macros defined in :file:`pvr_macros.h`.
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The intention is that these functions are mostly called from architecture
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specific entrypoints, that are handled by the common vulkan dispatch-table
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code. This means that an architecture specific function can easily call either
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architecture specific or architecture agnostic code.
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The tricky bit comes when architecture agnostic code calls architecture
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specific code. In that case, we have the ``PVR_ARCH_DISPATCH`` and
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``PVR_ARCH_DISPATCH_RET`` macros. These are a bit error-prone to use because
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they need to see definitions for all architecture versions of each entrypoint,
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which isn't something we have available. To work around this, we define a
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``PER_ARCH_FUNCS(arch)`` macro in each source-file that needs to use these
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dispatch macros and make sure to instantiate it once per architecture.
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To avoid confusion, please do not add functions that are prefixed with
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``pvr_arch_`` if they are not part of the system described here.
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drm-shim
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--------
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PowerVR implements ``drm-shim``, stubbing out the powervr DRM kernel interface.
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This allows for use-cases such as offline compiler testing and control-stream
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dumping.
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To build Mesa with the PowerVR drm-shim, configure Meson with
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``-Dvulkan-drivers=imagination`` and ``-Dtools=drm-shim``.
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The drm-shim binary will be built to
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``build/src/imagination/drm-shim/libpowervr_noop_drm_shim.so``.
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To use, set the ``LD_PRELOAD`` environment variable to the drm-shim binary.
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By default, drm-shim mocks a BXS-4-64 with a BVNC of 36.53.104.796,
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however this can be overridden by setting the ``PVR_SHIM_DEVICE_BVNC``
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environment variable. The value to set should match those found in the
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``struct pvr_device_ident`` instances defined in
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``src/imagination/common/device_info/*.h``.
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The reported quirks and enhancements can be overridden by setting the
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``PVR_SHIM_MUSTHAVE_QUIRKS``, ``PVR_SHIM_QUIRKS``, and ``PVR_SHIM_ENHANCEMENTS``
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environment variables. These should be set to a comma/semicolon-separated list
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of quirk/enhancement IDs.
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Chat
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----
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PowerVR developers and users hang out on IRC at ``#powervr`` on OFTC. Note
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that registering and authenticating with ``NickServ`` is required to prevent
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spam. `Join the chat. <https://webchat.oftc.net/?channels=powervr>`_
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Hardware glossary
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-----------------
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.. glossary:: :sorted:
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BVNC
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Set of four numbers used to uniquely identify each GPU (Series6 onwards).
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This is used to determine the GPU feature set, along with any known
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hardware issues.
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