add README.distro file

Add documentation on how to setup a system to use the generic distro
configs and boot commands. This spells out what is needed to make a
system conformant, but does not limit the board to only the defaults.

1 files changed, 76 insertions, 0 deletions

diff --git a/doc/README.distro b/doc/README.distro
new file mode 100644
index 0000000000..435c578c2b
--- /dev/null
+++ b/doc/README.distro
@@ -0,0 +1,76 @@
+/*
+ * (C) Copyright 2014 Red Hat Inc.
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+Generic distro configuration
+----------------------------
+
+configuring
+-----------
+To configure a board to run the generic distro setup and enable generic distros
+to easily support your board.
+
+you will need to include a pair of headers to enable the boot environment and
+configuration options needed. It is best to only include when not doing an
+SPL build.
+
+#ifndef CONFIG_SPL_BUILD
+#include <config_distro_defaults.h>
+#include <config_distro_bootcmd.h>
+#endif
+
+There is some memory addresses you will need to define in
+CONFIG_EXTRA_ENV_SETTINGS
+fdt_addr:
+Optional, If specified a dtb to boot the system must be available at the given
+address.
+
+fdt_addr_r:
+Mandatory, This is the location where the sysboot/pxeboot with load the dtb to,
+using the fdtdir/devicetreedir or fdt/devicetree options in the pxe/extlinux
+config file. The location can be anywhere in ram it just needs to not overlap
+with anything, allowing 1 megabyte seems to be a safe option.
+
+ramdisk_addr_r:
+Mandatory, This is the location where the sysboot/pxeboot with load the
+initramfs to, using the initrd option in the pxe/extlinux config file, the
+location of the initramfs does not matter, there needs to be enough room to be
+able to store any image. Making the image the last item stored should allow for
+any initramfs to fit and not overwrite anything else.
+
+kernel_addr_r:
+Mandatory, This is the location where the sysboot/pxeboot with load the kernel
+to,using the kernel option in the pxe/extlinux config file, the location of the
+kernel needs to 
+
+pxe_addr_r:
+Mandatory, used by the PXE code to hold the pxelinux config file. The location
+can be anywhere in ram it just needs to not overlap with anything, allowing 1 
+megabyte seems to be a safe option.
+
+scriptaddr:
+Mandatory, used to load boot.scr to The location can be anywhere in ram it just
+needs to not overlap with anything, allowing 1 megabyte seems to be a safe
+option.
+
+suggested mapping:
+For suggestions on memory locations for arm systems  you must follow the
+guidelines specified in Documentation/arm/Booting in the Linux kernel tree.
+For other architectures you must follow the guidelines for the architecture.
+
+make sure you also include BOOTCMDS_COMMON in CONFIG_EXTRA_ENV_SETTINGS
+
+You should not set initrd_high and fdt_high to 0xffffffff as the user should
+not need to edit the memory locations having the initramfs and dtb being
+relocatable is best to ensure the system will boot in all situations. 
+
+booting your system
+-------------------
+in the most simplest form CONFIG_BOOTCOMMAND just needs one line
+
+"for target in ${boot_targets}; do run bootcmd_${target}; done "
+
+you can run any setup before going through the targets for example run a
+command to set "fdtfile" variable for the dtb for your board.