diff --git a/docs/porting-guide.rst b/docs/porting-guide.rst
index 66fe0f1..4d4cdcd 100644
--- a/docs/porting-guide.rst
+++ b/docs/porting-guide.rst
@@ -60,11 +60,16 @@
 instruction and data caches for each BL stage. Setting up the translation
 tables is the responsibility of the platform port because memory maps differ
 across platforms. A memory translation library (see ``lib/xlat_tables/``) is
-provided to help in this setup. Note that although this library supports
-non-identity mappings, this is intended only for re-mapping peripheral physical
-addresses and allows platforms with high I/O addresses to reduce their virtual
-address space. All other addresses corresponding to code and data must currently
-use an identity mapping.
+provided to help in this setup.
+
+Note that although this library supports non-identity mappings, this is intended
+only for re-mapping peripheral physical addresses and allows platforms with high
+I/O addresses to reduce their virtual address space. All other addresses
+corresponding to code and data must currently use an identity mapping.
+
+Also, the only translation granule size supported in Trusted Firmware is 4KB, as
+various parts of the code assume that is the case. It is not possible to switch
+to 16 KB or 64 KB granule sizes at the moment.
 
 In ARM standard platforms, each BL stage configures the MMU in the
 platform-specific architecture setup function, ``blX_plat_arch_setup()``, and uses