doc: Move the generic memory-documentation to doc/

Move this section of the README into doc/ with some minor updates to
mention SPL and user lower-case hex.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

diff --git a/README b/README
index 4be1e8c22a0a5ab20532199864349e37bd4a7e4f..d73042406b68a52a5f49f1e4a82c665608646bc9 100644 (file)
--- a/README
+++ b/README
@@ -2516,51 +2516,6 @@ On RISC-V, the following registers are used:
 
     ==> U-Boot will use gp to hold a pointer to the global data
 
-Memory Management:
-------------------
-
-U-Boot runs in system state and uses physical addresses, i.e. the
-MMU is not used either for address mapping nor for memory protection.
-
-The available memory is mapped to fixed addresses using the memory
-controller. In this process, a contiguous block is formed for each
-memory type (Flash, SDRAM, SRAM), even when it consists of several
-physical memory banks.
-
-U-Boot is installed in the first 128 kB of the first Flash bank (on
-TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
-booting and sizing and initializing DRAM, the code relocates itself
-to the upper end of DRAM. Immediately below the U-Boot code some
-memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
-configuration setting]. Below that, a structure with global Board
-Info data is placed, followed by the stack (growing downward).
-
-Additionally, some exception handler code is copied to the low 8 kB
-of DRAM (0x00000000 ... 0x00001FFF).
-
-So a typical memory configuration with 16 MB of DRAM could look like
-this:
-
-       0x0000 0000     Exception Vector code
-             :
-       0x0000 1FFF
-       0x0000 2000     Free for Application Use
-             :
-             :
-
-             :
-             :
-       0x00FB FF20     Monitor Stack (Growing downward)
-       0x00FB FFAC     Board Info Data and permanent copy of global data
-       0x00FC 0000     Malloc Arena
-             :
-       0x00FD FFFF
-       0x00FE 0000     RAM Copy of Monitor Code
-       ...             eventually: LCD or video framebuffer
-       ...             eventually: pRAM (Protected RAM - unchanged by reset)
-       0x00FF FFFF     [End of RAM]
-
-
 System Initialization:
 ----------------------
 

diff --git a/doc/develop/index.rst b/doc/develop/index.rst
index 0d0e60ab56cb265543fb48adfbc79fd81d6ea257..cbea38d43235ea7194f15bc680931f3a475d5194 100644 (file)
--- a/doc/develop/index.rst
+++ b/doc/develop/index.rst
@@ -13,6 +13,7 @@ General
    codingstyle
    designprinciples
    docstyle
+   memory
    patman
    process
    release_cycle

diff --git a/doc/develop/memory.rst b/doc/develop/memory.rst
new file mode 100644 (file)
index 0000000..e9e65ba
--- /dev/null
+++ b/doc/develop/memory.rst
@@ -0,0 +1,49 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Memory Management
+-----------------
+
+.. note::
+
+  This information is outdated and needs to be updated.
+
+U-Boot runs in system state and uses physical addresses, i.e. the
+MMU is not used either for address mapping nor for memory protection.
+
+The available memory is mapped to fixed addresses using the
+memory-controller. In this process, a contiguous block is formed for each
+memory type (Flash, SDRAM, SRAM), even when it consists of several
+physical-memory banks.
+
+U-Boot is installed in XIP flash memory, or may be loaded into a lower region of
+RAM by a secondary program loader (SPL). After
+booting and sizing and initialising DRAM, the code relocates itself
+to the upper end of DRAM. Immediately below the U-Boot code some
+memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
+configuration setting]. Below that, a structure with global Board-Info
+data is placed, followed by the stack (growing downward).
+
+Additionally, some exception handler code may be copied to the low 8 kB
+of DRAM (0x00000000 ... 0x00001fff).
+
+So a typical memory configuration with 16 MB of DRAM could look like
+this::
+
+       0x0000 0000     Exception Vector code
+             :
+       0x0000 1fff
+       0x0000 2000     Free for Application Use
+             :
+             :
+
+             :
+             :
+       0x00fb ff20     Monitor Stack (Growing downward)
+       0x00fb ffac     Board Info Data and permanent copy of global data
+       0x00fc 0000     Malloc Arena
+             :
+       0x00fd ffff
+       0x00fe 0000     RAM Copy of Monitor Code
+       ...             eventually: LCD or video framebuffer
+       ...             eventually: pRAM (Protected RAM - unchanged by reset)
+       0x00ff ffff     [End of RAM]