[v3,00/15] env: Multiple env support and env transition for sunxi

Hi,

Here is a second attempt at transitioning away from the MMC raw environment
to a FAT-based one for Allwinner SoCs. Since the RFC was quite well
received, I actually tested it and fixed a few rough edges.

You'll find the first RFC here for reference:
https://lists.denx.de/pipermail/u-boot/2017-October/310111.html

And the second that originated in this series:
https://lists.denx.de/pipermail/u-boot/2017-November/311608.html

I gave it a travis run, and it passes all tests:
https://travis-ci.org/mripard/u-boot

Thanks!
Maxime

Original description of the patches:

The fundamental issue I'm trying to adress is that we've had for a
very long time the assumption that the main U-Boot binary wouldn't
exceed around 500 bytes.

However, we're starting to get real close to that limit, and are
running out of silver bullets to deal with the consequences of having
a bigger U-Boot binary, the main consequence being that we would
have some overlap between the environment and U-Boot.

One way to address this that has been suggested by Tom is to move away
from the raw MMC environment to a FAT-based one. This would allow us
to slowly migrate away, and eventually remove the MMC-raw option
entirely to reclaim that space for the binary.

That cannot be done in a single release however, since we might have
environments in the wild already that people rely on. And since we
always encouraged people to use the raw MMC environment, noone would
expect that.

This is even worse since some platforms are using the U-Boot
environment to deal with implement their upgrade mechanism, such as
mender.io, and force moving the environment would break any further
upgrade.

The suggested implementation is to allow U-Boot to compile multiple
environments backend at once, based on the work done by Simon. The
default behaviour shouldn't change obviously. We can then piggy-back
on this to tweak on a per-board basis the environment lookup algorithm
to always favour the FAT-based environment and then fallback to the
MMC. It will allow us to migrate a raw-MMC user to a FAT based
solution as soon as they update their environment (assuming that there
is a bootable FAT partition in the system).

This has just been compile tested on sunxi so far, and I'd like
general comments on the approach taken. Obviously, this will need to
work properly before being merged.

Changes from v2:
  - Fix a bug showing up on travis that resulted in the vexpress_ca_15 DHCP
    unit test failing. This was due to an improper return of ENVL_UNKNOWN.
  - Added Simon reviewed-by tag

Changes from v1:
  - Collect tags
  - Rebased on v2018.01
  - Fixed build failures on a couple of boards
  - Added back the message and the error code when an environment is
    failing
  - Added some comments about the printf in environments
  - Added a build time check about the number of our locations array to see
    if we're overflowing the location variable
  - Fixed the drv->init return code being ignored
  - Added helpers to manage the init status
  - Changed the ENVO prefix for the operations to ENVOP
  - Added some comments and documentation

Changes from the RFC:
  - Added more useful messages to see where we're loading / saving
  - Init all the environments no matter what, and the deal with whatever
    env we want to pick at load time
  - Added the various tags collected

Maxime Ripard (15):
  cmd: nvedit: Get rid of the env lookup
  env: Rename env_driver_lookup_default and env_get_default_location
  env: Pass additional parameters to the env lookup function
  env: Make the env save message a bit more explicit
  env: Make it explicit where we're loading our environment from
  env: fat: Make the debug messages play a little nicer
  env: mmc: Make the debug messages play a little nicer
  env: common: Make the debug messages play a little nicer
  env: Support multiple environments
  env: Initialise all the environments
  env: mmc: depends on the MMC framework
  env: Allow to build multiple environments in Kconfig
  env: Mark env_get_location as weak
  sunxi: Transition from the MMC to a FAT-based environment
  env: sunxi: Enable FAT-based environment support by default

 board/sunxi/board.c                   |  16 ++-
 cmd/nvedit.c                          |   4 +-
 configs/MPC8313ERDB_NAND_33_defconfig |   1 +-
 configs/MPC8313ERDB_NAND_66_defconfig |   1 +-
 configs/cl-som-imx7_defconfig         |   1 +-
 configs/microblaze-generic_defconfig  |   1 +-
 env/Kconfig                           |  70 ++++----
 env/common.c                          |   2 +-
 env/env.c                             | 251 +++++++++++++++++++--------
 env/fat.c                             |  25 ++-
 env/mmc.c                             |   1 +-
 include/asm-generic/global_data.h     |   1 +-
 include/environment.h                 |  15 +-
 13 files changed, 266 insertions(+), 123 deletions(-)

base-commit: f3dd87e0b98999a78e500e8c6d2b063ebadf535a