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diff --git a/doc/README.generic-board b/doc/README.generic-board deleted file mode 100644 index 50d3a26..0000000 --- a/doc/README.generic-board +++ /dev/null @@ -1,189 +0,0 @@ -# -# (C) Copyright 2014 Google, Inc -# Simon Glass <sjg@chromium.org> -# -# SPDX-License-Identifier: GPL-2.0+ -# - -DEPRECATION NOTICE FOR arch/<arch>/lib/board.c - -For board maintainers: Please submit patches for boards you maintain before -July 2014, to make them use generic board. - -For architecture maintainers: Please submit patches to remove your -architecture-specific board.c file before October 2014. - - -Background ----------- - -U-Boot has tranditionally had a board.c file for each architecture. This has -introduced quite a lot of duplication, with each architecture tending to do -initialisation slightly differently. To address this, a new 'generic board -init' feature was introduced a year ago in March 2013 (further motivation is -provided in the cover letter below). - - -What has changed? ------------------ - -The main change is that the arch/<arch>/lib/board.c file is being removed in -favour of common/board_f.c (for pre-relocation init) and common/board_r.c -(for post-relocation init). - -Related to this, the global_data and bd_t structures now have a core set of -fields which are common to all architectures. Architecture-specific fields -have been moved to separate structures. - - -Supported Arcthitectures ------------------------- - -If you are unlucky then your architecture may not support generic board. -The following architectures are supported at the time of writing: - - arc - arm - powerpc - sandbox - x86 - -If your architecture is not supported, you need to adjust your -arch/<arch>/config.mk file to include: - - __HAVE_ARCH_GENERIC_BOARD := y - -and test it with a suitable board, as follows. - - -Adding Support for your Board ------------------------------ - -To enable generic board for your board, define CONFIG_SYS_GENERIC_BOARD in -your board config header file. - -Test that U-Boot still functions correctly on your board, and fix any -problems you find. Don't be surprised if there are no problems - generic -board has had a reasonable amount of testing with common boards. - - -DeadLine --------- - -Please don't take this the wrong way - there is no intent to make your life -miserable, and we have the greatest respect and admiration for U-Boot users. -However, with any migration there has to be a period where the old way is -deprecated and removed. Every patch to the deprecated code introduces a -potential breakage in the new unused code. Therefore: - -Boards or architectures not converted over to general board by the -end of 2014 may be forcibly changed over (potentially causing run-time -breakage) or removed. - - - -Further Background ------------------- - -The full text of the original generic board series is reproduced below. - ---8<------------- - -This series creates a generic board.c implementation which contains -the essential functions of the major arch/xxx/lib/board.c files. - -What is the motivation for this change? - -1. There is a lot of repeated code in the board.c files. Any change to -things like setting up the baud rate requires a change in 10 separate -places. - -2. Since there are 10 separate files, adding a new feature which requires -initialisation is painful since it must be independently added in 10 -places. - -3. As time goes by the architectures naturely diverge since there is limited -pressure to compare features or even CONFIG options against simiilar things -in other board.c files. - -4. New architectures must implement all the features all over again, and -sometimes in subtley different ways. This places an unfair burden on getting -a new architecture fully functional and running with U-Boot. - -5. While it is a bit of a tricky change, I believe it is worthwhile and -achievable. There is no requirement that all code be common, only that -the code that is common should be located in common/board.c rather than -arch/xxx/lib/board.c. - -All the functions of board_init_f() and board_init_r() are broken into -separate function calls so that they can easily be included or excluded -for a particular architecture. It also makes it easier to adopt Graeme's -initcall proposal when it is ready. - -http://lists.denx.de/pipermail/u-boot/2012-January/114499.html - -This series removes the dependency on generic relocation. So relocation -happens as one big chunk and is still completely arch-specific. See the -relocation series for a proposed solution to this for ARM: - -http://lists.denx.de/pipermail/u-boot/2011-December/112928.html - -or Graeme's recent x86 series v2: - -http://lists.denx.de/pipermail/u-boot/2012-January/114467.html - -Instead of moving over a whole architecture, this series takes the approach -of simply enabling generic board support for an architecture. It is then up -to each board to opt in by defining CONFIG_SYS_GENERIC_BOARD in the board -config file. If this is not done, then the code will be generated as -before. This allows both sets of code to co-exist until we are comfortable -with the generic approach, and enough boards run. - -ARM is a relatively large board.c file and one which I can test, therefore -I think it is a good target for this series. On the other hand, x86 is -relatively small and simple, but different enough that it introduces a -few issues to be solved. So I have chosen both ARM and x86 for this series. -After a suggestion from Wolfgang I have added PPC also. This is the -largest and most feature-full board, so hopefully we have all bases -covered in this RFC. - -A generic global_data structure is also required. This might upset a few -people. Here is my basic reasoning: most fields are the same, all -architectures include and need it, most global_data.h files already have -#ifdefs to select fields for a particular SOC, so it is hard to -see why architecures are different in this area. We can perhaps add a -way to put architecture-specific fields into a separate header file, but -for now I have judged that to be counter-productive. - -Similarly we need a generic bd_info structure, since generic code will -be accessing it. I have done this in the same way as global_data and the -same comments apply. - -There was dicussion on the list about passing gd_t around as a parameter -to pre-relocation init functions. I think this makes sense, but it can -be done as a separate change, and this series does not require it. - -While this series needs to stand on its own (as with the link script -cleanup series and the generic relocation series) the goal is the -unification of the board init code. So I hope we can address issues with -this in mind, rather than focusing too narrowly on particular ARM, x86 or -PPC issues. - -I have run-tested ARM on Tegra Seaboard only. To try it out, define -CONFIG_SYS_GENERIC_BOARD in your board file and rebuild. Most likely on -x86 and PPC at least it will hang, but if you are lucky it will print -something first :-) - -I have run this though MAKEALL with CONFIG_SYS_GENERIC_BOARD on for all -ARM, PPC and x86 boards. There are a few failures due to errors in -the board config, which I have sent patches for. The main issue is -just the difference between __bss_end and __bss_end__. - -Note: the first group of commits are required for this series to build, -but could be separated out if required. I have included them here for -convenience. - -------------->8-- - -Simon Glass, sjg@chromium.org -March 2014 |