diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index ff7488cb63b93830f75093030add22d6f7a086c4..5693abb663e396d85c9b3c623c9e940e2b12037f 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -315,6 +315,15 @@ This machine is deprecated because we have enough AST2500 based OpenPOWER
 machines. It can be easily replaced by the ``witherspoon-bmc`` or the
 ``romulus-bmc`` machines.
 
+PPC 405 ``taihu`` machine (since 7.0)
+'''''''''''''''''''''''''''''''''''''
+
+The PPC 405 CPU is a system-on-a-chip, so all 405 machines are very similar,
+except for some external periphery. However, the periphery of the ``taihu``
+machine is hardly emulated at all (e.g. neither the LCD nor the USB part had
+been implemented), so there is not much value added by this board. Use the
+``ref405ep`` machine instead.
+
 Backend options
 ---------------
 
diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
index b4249f4626e6068ba5742ccd5e42d6903b22a21a..f1623aa622a6d5c7e53c779cf22bdd475c5771b2 100644
--- a/hw/ppc/ppc405_boards.c
+++ b/hw/ppc/ppc405_boards.c
@@ -547,6 +547,7 @@ static void taihu_class_init(ObjectClass *oc, void *data)
     mc->init = taihu_405ep_init;
     mc->default_ram_size = 0x08000000;
     mc->default_ram_id = "taihu_405ep.ram";
+    mc->deprecation_reason = "incomplete, use 'ref405ep' instead";
 }
 
 static const TypeInfo taihu_type = {