diff --git a/hw/sparc/sun4m.c b/hw/sparc/sun4m.c
index 07d126aea820bd44e35a252cba757490a02441ff..5151a7202ba9900d0d14c4361119eeebb45dc703 100644
--- a/hw/sparc/sun4m.c
+++ b/hw/sparc/sun4m.c
@@ -97,6 +97,25 @@ struct sun4m_hwdef {
     uint8_t nvram_machine_id;
 };
 
+const char *fw_cfg_arch_key_name(uint16_t key)
+{
+    static const struct {
+        uint16_t key;
+        const char *name;
+    } fw_cfg_arch_wellknown_keys[] = {
+        {FW_CFG_SUN4M_DEPTH, "depth"},
+        {FW_CFG_SUN4M_WIDTH, "width"},
+        {FW_CFG_SUN4M_HEIGHT, "height"},
+    };
+
+    for (size_t i = 0; i < ARRAY_SIZE(fw_cfg_arch_wellknown_keys); i++) {
+        if (fw_cfg_arch_wellknown_keys[i].key == key) {
+            return fw_cfg_arch_wellknown_keys[i].name;
+        }
+    }
+    return NULL;
+}
+
 static void fw_cfg_boot_set(void *opaque, const char *boot_device,
                             Error **errp)
 {