PowerVR

PowerVR is a Vulkan driver for Imagination Technologies PowerVR GPUs, starting with those based on the Rogue architecture.

The driver is conformant to Vulkan 1.0 on BXS-4-64, but not yet on other GPUs and Vulkan versions, so it requires exporting PVR_I_WANT_A_BROKEN_VULKAN_DRIVER=1 to the environment before running any Vulkan content.

The following hardware is currently in active development:

Product	Series	B.V.N.C	Vulkan
AXE-1-16M	A-Series	33.15.11.3	1.2
BXS-4-64	B-Series	36.53.104.796	1.2
BXM-4-64	B-Series	36.52.104.182	1.2
BXM-4-64	B-Series	36.56.104.183	1.2

The following hardware is partially supported and not currently under active development:

Product	Series	B.V.N.C	Vulkan	Notes
GX6250	Series 6XT	4.40.2.51	1.2	[1]

[1]

Various core-specific texture, compute, and other workarounds are currently unimplemented for this device. Some very simple Vulkan applications may run unhindered, but instability and corruption are to be expected until the aforementioned workarounds are in place.

The following hardware is unsupported and not under active development:

Product	Series	B.V.N.C
GX6250	Series 6XT	4.45.2.58
GX6650	Series 6XT	4.46.6.62
G6110	Series 6XE	5.9.1.46
GE7800	Series 7XE	15.5.1.64
GE8300	Series 8XE	22.67.54.30
GE8300	Series 8XE	22.68.54.30
GE8300	Series 8XE	22.102.54.38
BXE-2-32	B-Series	36.29.52.182
BXE-4-32	B-Series	36.50.54.182

Device info and firmware have been made available for these devices, typically due to community requests or interest, but no support is guaranteed beyond this.

In some cases, a product name is shared across multiple BVNCs so to check for support make sure the BVNC matches the one listed. As the feature set and hardware issues can vary between BVNCs, additional driver changes might be necessary even for devices sharing the same product name.

Hardware documentation can be found at: https://docs.imgtec.com/

Note: GPUs prior to Series6 do not have the hardware capabilities required to support Vulkan and therefore cannot be supported by this driver.

Multi-Architecture support

In order to support multiple distinct hardware generations without too much spaghetti-code, ther PowerVR compiles a few files multiple times (once per hardware architecture), and uses a system of macros and aliases to be able to refer to the different versions.

The files that gets compiled multiple times are those named pvr_arch_*.c. These files contains definitions of functions prefixed with pvr_arch_ (instead of the normal pvr_-prefix). The arch-bit of that function is a placeholder, which gets replaced at compile-time, thanks to a system of defines in the corresponding header file, supported by a set of macros defined in pvr_macros.h.

The intention is that these functions are mostly called from architecture specific entrypoints, that are handled by the common vulkan dispatch-table code. This means that a architecture specific function can easily call either architecture specific or architecture agnostic code.

The tricky bit comes when architecture agnostic calls architecture specific code. In that case, we have the PVR_ARCH_DISPATCH and PVR_ARCH_DISPATCH_RET macros. These are a bit error-prone to use, because they need to see definition for all architecture versions of each entrypoint, which isn’t something we have available. To work around this, we define a PER_ARCH_FUNCS(arch) macro in each source-file that needs to use these dispatch macros, and make sure to instantiate it once per architecture.

To avoid confusion, please do not add functions that are prefixed with pvr_arch_ if they are not part of the system described here.

Chat

PowerVR developers and users hang out on IRC at #powervr on OFTC. Note that registering and authenticating with NickServ is required to prevent spam. Join the chat.

Hardware glossary

BVNC

Set of four numbers used to uniquely identify each GPU (Series6 onwards). This is used to determine the GPU feature set, along with any known hardware issues.