FVP: make usage of Trusted DRAM optional at build time

This patch groups the current contents of the Trusted DRAM region at
address 0x00_0600_0000 (entrypoint mailboxes and BL3-1 parameters) in
a single shared memory area that may be allocated to Trusted SRAM
(default) or Trusted DRAM at build time by setting the
FVP_SHARED_DATA_LOCATION make variable. The size of this shared
memory is 4096 bytes.

The combination 'Shared data in Trusted SRAM + TSP in Trusted DRAM'
is not currently supported due to restrictions in the maximum number
of mmu tables that can be created.

Documentation has been updated to reflect these changes.

Fixes ARM-software/tf-issues#100

Change-Id: I26ff04d33ce4cacf8d770d1a1e24132b4fc53ff0

1 files changed, 15 insertions, 0 deletions

diff --git a/docs/user-guide.md b/docs/user-guide.md
index 4af9c286..fe9afb46 100644
--- a/docs/user-guide.md
+++ b/docs/user-guide.md
@@ -133,6 +133,8 @@ the build system doesn't track dependency for build options. Therefore, if any
 of the build options are changed from a previous build, a clean build must be
 performed.
 
+#### Common build options
+
 *   `BL30`: Path to BL3-0 image in the host file system. This image is optional.
     If a BL3-0 image is present then this option must be passed for the `fip`
     target
@@ -192,6 +194,19 @@ performed.
     synchronous method) or 1 (BL3-2 is initialized using asynchronous method).
     Default is 0.
 
+#### FVP specific build options
+
+*   `FVP_SHARED_DATA_LOCATION`: location of the shared memory page. Available
+    options:
+      - 'tsram' (default) : top of Trusted SRAM
+      - 'tdram' : base of Trusted DRAM
+
+*   `FVP_TSP_RAM_LOCATION`: location of the TSP binary. Options:
+      - 'tsram' (default) : base of Trusted SRAM
+      - 'tdram' : Trusted DRAM (above shared data)
+
+For a better understanding of FVP options, the FVP memory map is detailed in
+[Firmware Design].
 
 ### Creating a Firmware Image Package