Merge c7e8c56c1b into d99198819c

Since currently there is only one device type (devicetree), chid_match()
compares the descriptor value of this device type directly and errors out for
other descriptors. When other device types will be added, this logic will fail.

Introduce DEVICE_TYPE_MAX to denote maximum value of a device type and use
the corresponding descriptor to do validations in chid_match.

src/boot/chid.c

@@ -113,7 +113,7 @@ EFI_STATUS chid_match(const void *hwid_buffer, size_t hwid_length, const Device
 
                 if (devices[n_devices].descriptor == DEVICE_DESCRIPTOR_EOL)
                         break;
-                if (devices[n_devices].descriptor != DEVICE_DESCRIPTOR_DEVICETREE)
+                if (devices[n_devices].descriptor >= DEVICE_DESCRIPTOR_MAX)
                         return EFI_UNSUPPORTED;
                 n_devices++;
         }

src/boot/chid.h

@@ -16,6 +16,7 @@ enum {
          *   - CoCo Bring-Your-Own-Firmware
          *   - ACPI DSDT Overrides
          *   - … */
+        _DEVICE_TYPE_MAX,
 };
 
 #define DEVICE_SIZE_FROM_DESCRIPTOR(u) ((uint32_t) (u) & UINT32_C(0x0FFFFFFF))
@@ -23,6 +24,7 @@ enum {
 #define DEVICE_MAKE_DESCRIPTOR(type, size) (((uint32_t) (size) | ((uint32_t) type << 28)))
 
 #define DEVICE_DESCRIPTOR_DEVICETREE DEVICE_MAKE_DESCRIPTOR(DEVICE_TYPE_DEVICETREE, sizeof(Device))
+#define DEVICE_DESCRIPTOR_MAX DEVICE_MAKE_DESCRIPTOR(_DEVICE_TYPE_MAX, sizeof(Device))
 #define DEVICE_DESCRIPTOR_EOL UINT32_C(0)
 
 typedef struct Device {