[igt-dev] [PATCH i-g-t v21 01/35] lib/gem_submission: Add gem_has_relocations() check

[Chris Wilson]

Quoting Zbigniew Kempczyński (2021-03-01 16:13:29)
> Add check which probes kernel supports relocation or not
> for i915 device.
> 
> Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Dominik Grzegorzek <dominik.grzegorzek at intel.com>
> Cc: Petri Latvala <petri.latvala at intel.com>
> ---
>  lib/i915/gem_submission.c | 30 ++++++++++++++++++++++++++++++
>  lib/i915/gem_submission.h |  1 +
>  2 files changed, 31 insertions(+)
> 
> diff --git a/lib/i915/gem_submission.c b/lib/i915/gem_submission.c
> index 320340a5d..051f9d046 100644
> --- a/lib/i915/gem_submission.c
> +++ b/lib/i915/gem_submission.c
> @@ -398,3 +398,33 @@ unsigned int gem_submission_measure(int i915, unsigned int engine)
>  
>         return size;
>  }
> +
> +/**
> + * gem_has_relocations:
> + * @fd: opened i915 drm file descriptor
> + *
> + * Feature test macro to query whether kernel allows for generation to
> + * use relocations.
> + *
> + * Returns: true if we can use relocations, otherwise false
> + */
> +
> +bool gem_has_relocations(int i915)
> +{
> +       struct drm_i915_gem_relocation_entry reloc = {};
> +       struct drm_i915_gem_exec_object2 obj = {
> +               .handle = gem_create(i915, 4096),
> +               .relocs_ptr = to_user_pointer(&reloc),
> +               .relocation_count = 1,
> +       };
> +       struct drm_i915_gem_execbuffer2 execbuf = {
> +               .buffers_ptr = to_user_pointer(&obj),
> +               .buffer_count = 1,
> +       };
> +       bool has_relocs;
> +
> +       has_relocs = __gem_execbuf(i915, &execbuf) == -ENOENT;
> +       gem_close(i915, obj.handle);

Everything but for the relocation, so the first error we hit will be the
validation of that relocation.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris