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.
Signed-off-by: Dennis Gilmore dennis@ausil.us --- doc/README.distro | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 doc/README.distro
diff --git a/doc/README.distro b/doc/README.distro new file mode 100644 index 0000000..435c578 --- /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.