[Intel-gfx] [RFC] drm/i915/guc: capture GuC logs if FW fails to load

[Chris Wilson]

On Thu, May 04, 2017 at 09:26:35PM +0000, Srivatsa, Anusha wrote:
> >+void i915_guc_load_error_log_capture(struct drm_i915_private *i915) {
> >+	void *log, *buf;
> >+	struct i915_vma *vma = i915->guc.log.vma;
> >+
> >+	if (i915->gpu_error.guc_load_fail_log || !vma)
> >+		return;
> >+
> >+	/*
> >+	 * the vma should be already pinned and mapped for log runtime
> >+	 * management but let's play safe
> >+	 */
> >+	log = i915_gem_object_pin_map(vma->obj, I915_MAP_WC);
> >+	if (IS_ERR(log)) {
> >+		DRM_ERROR("Failed to pin guc_log vma\n");
> >+		return;
> >+	}
> >+
> >+	buf = kzalloc(GUC_LOG_SIZE, GFP_KERNEL);
> >+	if (buf) {
> >+		memcpy(buf, log, GUC_LOG_SIZE);
> >+		i915->gpu_error.guc_load_fail_log = buf;
> >+	} else {
> >+		DRM_ERROR("Failed to copy guc log\n");
> >+	}
> >+
> >+	i915_gem_object_unpin_map(vma->obj);

You are trading a swappable object for unswappable kernel memory. If you
want to have the guc log after guc is disabled, just keep the log object
around.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre