On Wed, Aug 20, 2025 at 7:58 AM Srinivasan Shanmugam <srinivasan.shanmu...@amd.com> wrote: > > This series introduces a kernel-managed singleton BO representing the > MMIO-remap (HDP flush) page and exposes it to userspace through a new > GEM domain. > > Design ------ > - A tiny (1-page) TTM bucket is introduced for AMDGPU_PL_MMIO_REMAP > (mirroring doorbells). > - A singleton BO is created during amdgpu_ttm_init() and freed at > fini(). > - The BO is kernel-owned and never evicted. > - amdgpu_gem_create_ioctl() recognizes the new GEM domain bit > (AMDGPU_GEM_DOMAIN_MMIO_REMAP) and returns a handle to the pre-created > singleton BO, enforcing size/alignment checks. > - Userspace thus gets a stable GEM handle and can mmap it to issue HDP > flushes. > > * Only compilation tested so far (x86_64, defconfig + amdgpu enabled). > * No runtime validation yet. > > Cc: Christian König <christian.koe...@amd.com> > Cc: Alex Deucher <alexander.deuc...@amd.com> > > Srinivasan Shanmugam (7): > drm/amdgpu/uapi: add AMDGPU_GEM_DOMAIN_MMIO_REMAP > drm/amdgpu: Add New TTM Placement - AMDGPU_PL_MMIO_REMAP and wire up > plumbing > drm/amdgpu: Plumbing for MMIO_REMAP memtype and user-visible strings > drm/amdgpu: Add mmio_remap fields to amdgpu_device > drm/amdgpu: Implement TTM handling for MMIO_REMAP placement > drm/amdgpu: Create Singleton MMIO_REMAP BO and Initialize its pool > drm/amdgpu: Return Handle to MMIO_REMAP Singleton for GEM Create
You also need a patch which sets adev->mmio_remap.base and adev->mmio_remap.size. E.g., adev->mmio_remap.base = adev->rmmio_remap.bus_addr; adev->mmio_remap.size = 4096; Better yet, replace adev->rmmio_remap.bus_addr with adev->mmio_remap.base and just use that everywhere. Alex > > drivers/gpu/drm/amd/amdgpu/amdgpu.h | 7 ++ > drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c | 1 + > drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 56 +++++++++ > drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 13 ++ > drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 2 + > .../gpu/drm/amd/amdgpu/amdgpu_res_cursor.h | 2 + > drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 112 +++++++++++++++++- > drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 3 +- > include/drm/ttm/ttm_resource.h | 2 +- > include/uapi/drm/amdgpu_drm.h | 8 +- > 10 files changed, 198 insertions(+), 8 deletions(-) > > -- > 2.34.1 >
