Re: [PATCH v4 00/18] 48-bit PPGTT

Michel Thierry
2015-07-10T10:24:10Z

On 7/10/2015 10:39 AM, Chris Wilson wrote:
> On Tue, Jul 07, 2015 at 04:14:45PM +0100, Michel Thierry wrote:
>> These are the rebased patches, after Mika's final ppgtt clean-up series landed
>> (it relies in the macros added) and Akash review comments.
>>
>> In order expand the GPU address space, a 4th level translation is added, the
>> Page Map Level 4 (PML4). This PML4 has 256 PML4 Entries (PML4E), PML4[0-255],
>> each pointing to a PDP. All the existing "dynamic alloc ppgtt" functions are
>> used, only adding the 4th level changes. I also updated some remaining
>> variables that were 32b only.
>>
>> There are 2 hardware workarounds needed to allow correct operation with 48b
>> addresses (Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset). This
>> new patchset version includes the comments and suggestions from Chris Wilson.
>> A flag (EXEC_OBJECT_SUPPORTS_48B_ADDRESS) will indicate if a given object can be
>> allocated outside the first 4 PDPs; if not, the end range is forced to 4GB. Also,
>> more objects now use the DRM_MM_CREATE_TOP flag. To maintain compatibility, in
>> libdrm I added a new drm_intel_bo_emit_reloc_48bit function that will flag
>> these objects, while the existing drm_intel_bo_emit_reloc clears it.
>>
>> Finally, this feature is only available in BDW and Gen9, requires LRC submission
>> mode (execlists) and it can be detected by i915.enable_ppgtt=3.
>>
>> Also note that this expanded address space is only available for full PPGTT,
>> aliasing PPGTT and Global GTT remain 32-bit.
>> Michel Thierry (18):
>> drm/i915: Remove unnecessary gen8_clamp_pd
>> drm/i915/gen8: Make pdp allocation more dynamic
>> drm/i915/gen8: Add PML4 structure
>> drm/i915/gen8: Abstract PDP usage
>> drm/i915/gen8: Add dynamic page trace events
>> drm/i915/gen8: implement alloc/free for 4lvl
>> drm/i915/gen8: Add 4 level switching infrastructure and lrc support
>> drm/i915/gen8: Generalize PTE writing for GEN8 PPGTT
>> drm/i915/gen8: Pass sg_iter through pte inserts
>> drm/i915/gen8: Add 4 level support in insert_entries and clear_range
>> drm/i915/gen8: Initialize PDPs
>> drm/i915: Expand error state's address width to 64b
>> drm/i915/gen8: Add ppgtt info and debug_dump
>> drm/i915: object size needs to be u64
>> drm/i915: batch_obj vm offset must be u64
>> drm/i915/userptr: Kill user_size limit check
>> drm/i915: Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset
>> drm/i915/gen8: Flip the 48b switch
>
> By the days end, I hope to be in a position to actually test large
> apertures on a real machine. Do you have a tree I can use?
> -Chris
>
Yes, use github.com/mthierry/drm-intel.git 48b-ppgtt-20150707