--- i/sys/dev/acpica/acpi.c
+++ w/sys/dev/acpica/acpi.c
@@ -183,6 +183,7 @@ static void acpi_enable_pcie(void);
 static void    acpi_hint_device_unit(device_t acdev, device_t child,
                    const char *name, int *unitp);
 static void    acpi_reset_interfaces(device_t dev);
+static bus_dma_tag_t acpi_get_dma_tag(device_t dev, device_t child);

 static device_method_t acpi_methods[] = {
     /* Device interface */
@@ -217,6 +218,7 @@ static device_method_t acpi_methods[] = {
     DEVMETHOD(bus_hint_device_unit,    acpi_hint_device_unit),
     DEVMETHOD(bus_get_cpus,            acpi_get_cpus),
     DEVMETHOD(bus_get_domain,          acpi_get_domain),
+    DEVMETHOD(bus_get_dma_tag,         acpi_get_dma_tag),

     /* ACPI bus */
     DEVMETHOD(acpi_id_probe,           acpi_device_id_probe),
@@ -430,6 +432,25 @@ acpi_identify(void)
     return (0);
 }

+static bus_dma_tag_t
+acpi_get_dma_tag(device_t dev, device_t child)
+{
+    bus_dma_tag_t result;
+
+    // TODO: get acpi handle of child, walk up the dsdt and get _DMA (and _CCA) data
+    // like NetBSD: https://github.com/NetBSD/src/blob/792df501ab0f93d73372a9bc2c7f19ccb733c1e5/sys/arch/arm/acpi/acpi_machdep.c#L400
+
+    if (bus_dma_tag_create(bus_get_dma_tag(dev), 1, 0,
+      0xbfffffff /* 3GB */, BUS_SPACE_MAXADDR, NULL, NULL,
+      BUS_SPACE_MAXSIZE, BUS_SPACE_UNRESTRICTED, BUS_SPACE_MAXSIZE,
+      /* BUS_DMA_COHERENT */ 0, NULL, NULL,
+      &result)) {
+          printf("disaster\n");
+    }
+
+    return (result);
+}
+
 /*
  * Fetch some descriptive data from ACPI to put in our attach message.
  */