Re: In flash vs compiled environment for omap, rasp-pi, socfpga

[Trent Piepho <tpiepho@kymetacorp.com>]

On Wed, 2015-10-21 at 07:30 +0200, Sascha Hauer wrote:
> > So why does loading the env from a FAT partition depend on
> > DEFAULT_ENVIRONMENT?  It does in the omap and socfpga code, but in the
> > rasp-pi code it doesn't.
> 
> It seems we just picked the wrong define to depend on. Maybe the ifdef
> CONFIG_DEFAULT_ENVIRONMENT in the omap code should just be dropped.

I've changed socfpga to depend on the xloader option instead, so that
the env loading function is not present in the xloader.  This seems to
work and gives me a booting xloader and main barebox with the in-flash
env.

> > If you turn it on, then you get the env in the FAT partition.  But you
> > also get the env compiled into the barebox binary.  If there are large
> > FPGA images stored in the env, this is very undesirable!
> 
> I do not really understand you here. Do you mean you compile the FPGA
> images into the default environment so that they end up being part of
> the barebox image, or do you mean you store the FPGA image in the
> environment in the FAT partition?

The latter.  But turning on DEFAULT_ENVIRONMENT will also try to give
you the former.  This may very well not be the best way to present fpga
images to barebox to load, but it still seems like the flash env loading
code is using the wrong config option.


> I think the environment specific config options are in most cases either
> all turned on or all turned off. Normally you want to have them turned
> on, but in some cases like omap xloader there's no environment at all
> and the options are all turned off. That could be the reason the
> dependencies are a bit inconsistent, nobody really tries to enable half
> of them. Anyway, patches welcome.

A survey of the defconfigs shows that 25 do not have
DEFAULT_ENVIRONMENT.  Of these 14 are omap, socfpga, imx, or at91
xloaders.  Of the remaining eleven, 5 have env commands enabled, 3 have
selected the simple shell which turns on environment variables, and the
remaining 3 get the HUSH shell by default which also has environment
variables.

So it seems there are just a handful of boards (11) that do have env
support but don't compile in a default environment.

Three are OMAP boards, omap3530_beagle_per_uart,
omap3430_sdp3430_per_uart, and omap3_evm.  AFAICT, they have no env in
flash anywhere, since they have turned off the generic env in FAT
support in omap (by turning off compiled in support), have no board
calls to default_environment_path_set() to change the env partition
from /dev/env0, have no calls to devfs_add_partition() to
create /dev/env0, and have OF tree support to create a partition that
way.

Is a barebox config with no compiled in env and no in flash env yet with
env support valid?  One does get an error message from barebox if you do
this.  I wonder if these three boards really want to disable the generic
OMAP env in FAT support without substituting anything in its place.
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