Re: [PATCH 2/4] tests/intel/xe_oa: Do not assume OA buffer is prefilled with zeroes

On Fri, 17 Jul 2026 14:00:30 -0700, Umesh Nerlige Ramappa wrote:
>
> The tail address test assumes that the OA buffer is preset to zeroes. Modify
> logic to be independent of this assumption.

Are we going to stop memset'ing OA buffer to 0 in the kernel? Even
otherwise, because this patch is a generalization of the OA buffer being 0:

Reviewed-by: Ashutosh Dixit <[email protected]>


>
> Signed-off-by: Umesh Nerlige Ramappa <[email protected]>
> ---
>  tests/intel/xe_oa.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/tests/intel/xe_oa.c b/tests/intel/xe_oa.c
> index e7e4f5601b61..98f00d377a86 100644
> --- a/tests/intel/xe_oa.c
> +++ b/tests/intel/xe_oa.c
> @@ -4634,7 +4634,7 @@ static void closed_fd_and_unmapped_access(const struct drm_xe_oa_unit *oau)
>   * format size is not a power of 2. This means that the last report will not be
>   * broken down across the OA buffer end. Instead it will be written to the
>   * beginning of the OA buffer. We will check the end of the buffer to ensure it
> - * has zeroes in it.
> + * has not been written into.
>   */
>  static void
>  test_tail_address_wrap(const struct drm_xe_oa_unit *oau, size_t oa_buffer_size)
> @@ -4649,6 +4649,7 @@ test_tail_address_wrap(const struct drm_xe_oa_unit *oau, size_t oa_buffer_size)
>		DRM_XE_OA_PROPERTY_OA_METRIC_SET, test_set->perf_oa_metrics_set,
>		DRM_XE_OA_PROPERTY_OA_FORMAT, __ff(fmt),
>		DRM_XE_OA_PROPERTY_OA_PERIOD_EXPONENT, exponent,
> +		DRM_XE_OA_PROPERTY_OA_DISABLED, true,
>		DRM_XE_OA_PROPERTY_OA_BUFFER_SIZE, buffer_size,
>	};
>	struct intel_xe_oa_open_prop param = {
> @@ -4656,25 +4657,31 @@ test_tail_address_wrap(const struct drm_xe_oa_unit *oau, size_t oa_buffer_size)
>		.properties_ptr = to_user_pointer(properties),
>	};
>	u32 fmt_size = get_oa_format(fmt).size;
> -	u32 zero_size = buffer_size % fmt_size;
> -	u32 *zero_area, *buffer_end, *buffer_start;
> +	u32 area_size = buffer_size % fmt_size;
> +	u32 *area, *buffer_end, *buffer_start;
> +	u32 *content = malloc(area_size);
>
> -	igt_require(zero_size);
> +	igt_require(area_size);
> +	igt_require(content);

igt_assert(content);

>
>	stream_fd = __perf_open(drm_fd, &param, false);
>	set_fd_flags(stream_fd, O_CLOEXEC);
> -
> -	wait_for_oa_buffer_overflow(stream_fd, 100);
> -
>	buffer_start = mmap(0, buffer_size, PROT_READ, MAP_PRIVATE, stream_fd, 0);
>	igt_assert(buffer_start);
>
> -	zero_area = buffer_start + (buffer_size - zero_size) / 4;
> +	area = buffer_start + (buffer_size - area_size) / 4;
>	buffer_end = buffer_start + buffer_size / 4;
>
> -	dump_report(zero_area, zero_size / 4, "zero_area");
> -	while (zero_area < buffer_end)
> -		igt_assert_eq(*zero_area++, 0);
> +	memcpy(content, area, area_size);
> +	dump_report(area, area_size / 4, "contents before");
> +
> +	do_ioctl(stream_fd, DRM_XE_OBSERVATION_IOCTL_ENABLE, 0);
> +	wait_for_oa_buffer_overflow(stream_fd, 100);
> +	do_ioctl(stream_fd, DRM_XE_OBSERVATION_IOCTL_DISABLE, 0);
> +
> +	dump_report(area, area_size / 4, "contents after");
> +	while (area < buffer_end)
> +		igt_assert_eq(*area++, *content++);
>
>	munmap(buffer_start, buffer_size);
>
> --
> 2.51.0
>