[PATCH 0/3] arm: mvebu: Espressobin: Set default env values at runtime

[Pali Rohár]

Hello!

On Tuesday 12 January 2021 09:18:44 Andre Heider wrote:
> Hi Pali,
> 
> On 11/01/2021 11:51, Pali Rohár wrote:
> > Hello Stefan and Andre!
> > 
> > Could you please look at this patch series and tell me what do you think
> > about it? If it is fine or needs to take different approach?
> 
> I like the idea very much, and I bet there're quite some boards which could
> make good use of "immutable envvars".
> 
> The obvious review point is the filler thing and its dependency on
> DEFAULT_ENV_IS_RW, which probably won't win a beauty contest :) Maybe a
> nicer integration would help in getting it merged?
> 
> I don't think it would take too much effort, first thing that comes to mind:
> - board provides list of immutable vars
> - env_set_default() backs up these vars
> - env_set_default() imports default_environment
> - env_set_default() imports backup on top
> 
> The last step should be easy, see env_set_default_vars().

This could probably work for $ethNaddr variables.

But there is still an issue how to handle $fdtfile. There is basically
default value for this variable, but value itself cannot be determined
at compile time, only at runtime. And for it variable flags do not help,
we just need an mechanism how to set default variable values not only at
compile time but also runtime.

That is why I chosen for now solution with modifying
default_environment[] array as it solve issue for both $fdtfile and
$ethNaddr variables.

> Maybe the first step can be solved with ENV_FLAGS_VAR, a new immutable flag,
> and boards just making use of CONFIG_ENV_FLAGS_LIST_DEFAULT to declare
> those. But I fail to find an example in-tree.
> 
> Thanks,
> Andre
> 
> > 
> > On Wednesday 23 December 2020 12:21:27 Pali Rohár wrote:
> > > This patch series set default env values of $fdtfile and $ethNaddr for
> > > Espressobin board at runtime.
> > > 
> > > It fixes two main issues on Espressobin board that 'env default -a'
> > > completely erases permanent board MAC addresses and also erase $fdtfile
> > > variable which is needed for booting Linux kernel via distro boot.
> > > 
> > > Lot of people were complaining about erasing permanent MAC addresses by
> > > U-boot on this board and due to this issue some linux distributions
> > > started using static hardcoded MAC addresses for all Espressobin boards
> > > to workaround this issue. Apparently erase of MAC addresses or usage of
> > > static hardcoded value caused more issues on network (e.g. inability to
> > > connect two of these boards to the same network).
> > > 
> > > Pali Rohár (3):
> > >    env: Allow to set default_environment[] from board code via compile
> > >      option DEFAULT_ENV_IS_RW
> > >    arm: mvebu: Espressobin: Set default value for $fdtfile env variable
> > >    arm: mvebu: Espressobin: Set default value for $ethNaddr env variable
> > > 
> > >   board/Marvell/mvebu_armada-37xx/board.c | 41 ++++++++++++++++++++-----
> > >   include/configs/mvebu_armada-37xx.h     | 17 +++++++++-
> > >   include/env_default.h                   |  2 ++
> > >   include/env_internal.h                  |  4 +++
> > >   4 files changed, 56 insertions(+), 8 deletions(-)
> > > 
> > > -- 
> > > 2.20.1
> > > 
>