Re: [igt-dev] [PATCH i-g-t 1/7] lib/gem_submission: Add kernel exec object alignment capability

From: "Dixit, Ashutosh" <ashutosh.dixit@intel.com>
To: "Zbigniew Kempczyński" <zbigniew.kempczynski@intel.com>
Cc: igt-dev@lists.freedesktop.org, Petri Latvala <petri.latvala@intel.com>
Subject: Re: [igt-dev] [PATCH i-g-t 1/7] lib/gem_submission: Add kernel exec object alignment capability
Date: Tue, 12 Oct 2021 21:47:18 -0700	[thread overview]
Message-ID: <87k0ihpm3t.wl-ashutosh.dixit@intel.com> (raw)
In-Reply-To: <20211008065432.15482-2-zbigniew.kempczynski@intel.com>

On Thu, 07 Oct 2021 23:54:26 -0700, Zbigniew Kempczyński wrote:
>
> +bool gem_allows_passing_alignment(int fd)
> +{
> +	struct drm_i915_gem_exec_object2 obj = {
> +		.handle = gem_create(fd, 4096),
> +	};
> +	struct drm_i915_gem_execbuffer2 execbuf = {
> +		.buffers_ptr = to_user_pointer(&obj),
> +		.buffer_count = 1,
> +	};
> +	bool ret;
> +	const uint32_t bbe = MI_BATCH_BUFFER_END;
> +
> +	gem_write(fd, obj.handle, 0, &bbe, sizeof(bbe));
> +	gem_execbuf(fd, &execbuf);
> +
> +	obj.alignment = 0x2000;

8K? Shouldn't this be less than 4K?

> +	ret = __gem_execbuf(fd, &execbuf) == 0;
> +	gem_close(fd, obj.handle);
> +
> +	return ret;
> +}