diff --git a/docs/plat/allwinner.rst b/docs/plat/allwinner.rst
index d82380d..1a9388b 100644
--- a/docs/plat/allwinner.rst
+++ b/docs/plat/allwinner.rst
@@ -5,22 +5,8 @@
 SoCs with ARMv8 cores. Only BL31 is used to provide proper EL3 setup and
 PSCI runtime services.
 
-U-Boot's SPL acts as a loader, loading both BL31 and BL33 (typically U-Boot).
-Loading is done from SD card, eMMC or SPI flash, also via an USB debug
-interface (FEL).
-
-BL31 lives in SRAM A2, which is documented to be accessible from secure
-world only.
-
-Current limitations:
-
--  Missing PMIC support
-
-After building bl31.bin, the binary must be fed to the U-Boot build system
-to include it in the FIT image that the SPL loader will process.
-bl31.bin can be either copied (or sym-linked) into U-Boot's root directory,
-or the environment variable BL31 must contain the binary's path.
-See the respective `U-Boot documentation`_ for more details.
+Building TF-A
+-------------
 
 To build for machines with an A64 or H5 SoC:
 
@@ -34,8 +20,58 @@
 
     make CROSS_COMPILE=aarch64-linux-gnu- PLAT=sun50i_h6 DEBUG=1 bl31
 
+
+Installation
+------------
+
+U-Boot's SPL acts as a loader, loading both BL31 and BL33 (typically U-Boot).
+Loading is done from SD card, eMMC or SPI flash, also via an USB debug
+interface (FEL).
+
+After building bl31.bin, the binary must be fed to the U-Boot build system
+to include it in the FIT image that the SPL loader will process.
+bl31.bin can be either copied (or sym-linked) into U-Boot's root directory,
+or the environment variable BL31 must contain the binary's path.
+See the respective `U-Boot documentation`_ for more details.
+
 .. _U-Boot documentation: https://gitlab.denx.de/u-boot/u-boot/-/blob/master/board/sunxi/README.sunxi64
 
+Memory layout
+-------------
+
+A64, H5 and H6 SoCs
+~~~~~~~~~~~~~~~~~~~
+
+BL31 lives in SRAM A2, which is documented to be accessible from secure
+world only. Since this SRAM region is very limited (48 KB), we take
+several measures to reduce memory consumption. One of them is to confine
+BL31 to only 28 bits of virtual address space, which reduces the number
+of required page tables (each occupying 4KB of memory).
+The mapping we use on those SoCs is as follows:
+
+::
+
+   0 64K         16M             1GB         1G+160M     physical address
+   +-+------+-+---+------+--...---+-------+----+------+----------
+   |B|      |S|///|      |//...///|       |////|      |
+   |R| SRAM |C|///| dev  |//...///| (sec) |////| BL33 |  DRAM ...
+   |O|      |P|///| MMIO |//...///| DRAM  |////|      |
+   |M|      | |///|      |//...///| (32M) |////|      |
+   +-+------+-+---+------+--...---+-------+----+------+----------
+   | |      | |   |      |       /       /   /      /
+   | |      | |   |      |      /       /  /      /
+   | |      | |   |      |     /       / /      /
+   | |      | |   |      |    /       //      /
+   | |      | |   |      |   /       /      /
+   +-+------+-+---+------+--+-------+------+
+   |B|      |S|///|      |//|       |      |
+   |R| SRAM |C|///| dev  |//|  sec  | BL33 |
+   |O|      |P|///| MMIO |//| DRAM  |      |
+   |M|      | |///|      |//|       |      |
+   +-+------+-+---+------+--+-------+------+
+   0 64K         16M       160M    192M  256M             virtual address
+
+
 Trusted OS dispatcher
 ---------------------