23.04.2021 19:32, Thierry Reding пишет:

+void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
+{
+	struct of_phandle_iterator it;
+	int err;
+
+	of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
+		struct iommu_resv_region *region;
+		struct of_phandle_args args;
+		struct resource res;
+
+		args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
+
+		err = of_address_to_resource(it.node, 0, &res);
+		if (err < 0) {
+			dev_err(dev, "failed to parse memory region %pOF: %d\n",
+				it.node, err);
+			continue;
+		}
+
+		if (args.args_count > 0) {
+			/*
+			 * Active memory regions are expected to be accessed by hardware during
+			 * boot and must therefore have an identity mapping created prior to the
+			 * driver taking control of the hardware. This ensures that non-quiescent
+			 * hardware doesn't cause IOMMU faults during boot.
+			 */
+			if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
+				region = iommu_alloc_resv_region(res.start, resource_size(&res),
+								 IOMMU_READ | IOMMU_WRITE,
+								 IOMMU_RESV_DIRECT_RELAXABLE);
+				if (!region)
+					continue;
+
+				list_add_tail(&region->list, list);
+			}
+		}
+	}
+}
+EXPORT_SYMBOL(of_iommu_get_resv_regions);

Any reason why this is not EXPORT_SYMBOL_GPL? I'm curious what is the
logic behind the OF symbols in general since it looks like half of them
are GPL.