[00/14] env: Multiple env support and env transition for sunxi

Message ID cover.f8d15c19daa14158145260d790deac55f3c66fb3.1511864667.git-series.maxime.ripard@free-electrons.com
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  • env: Multiple env support and env transition for sunxi
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Maxime Ripard Nov. 28, 2017, 10:24 a.m.
Hi,

Here is an attempt at transitioning away from the MMC raw environment to a
FAT-based one. 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

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.

Let me know what you think,
Maxime

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 (14):
  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: 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 +-
 env/Kconfig                       |  69 +++++------
 env/common.c                      |   2 +-
 env/env.c                         | 198 +++++++++++++++++++------------
 env/fat.c                         |   9 +-
 env/mmc.c                         |   1 +-
 include/asm-generic/global_data.h |   1 +-
 include/environment.h             |  14 +-
 9 files changed, 192 insertions(+), 122 deletions(-)

base-commit: c253573f3e269fd9a24ee6684d87dd91106018a5

Comments

Tom Rini Dec. 7, 2017, 8:09 p.m. | #1
On Tue, Nov 28, 2017 at 11:24:35AM +0100, Maxime Ripard wrote:

> Hi,

> 

> Here is an attempt at transitioning away from the MMC raw environment to a

> FAT-based one. 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

> 

> 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.

> 

> Let me know what you think,


I think this is the right direction to head in.  Can you please address
the few outstanding points / questions and have something posted shortly
after v2018.01 releases, and I'll apply it for inclusion in v2018.03?
Thanks!

-- 
Tom
Maxime Ripard Dec. 8, 2017, 9:05 a.m. | #2
Hi Tom,

On Thu, Dec 07, 2017 at 03:09:31PM -0500, Tom Rini wrote:
> > Here is an attempt at transitioning away from the MMC raw environment to a

> > FAT-based one. 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

> > 

> > 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.

> > 

> > Let me know what you think,

> 

> I think this is the right direction to head in.  Can you please address

> the few outstanding points / questions


This is done already.

> and have something posted shortly after v2018.01 releases, and I'll

> apply it for inclusion in v2018.03?


And I was waiting for your feedback :)

I'll do that, thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com