[U-Boot] [PATCH v4 6/6] common: Generic loader for file system

[Simon Glass]

Hi,

On 25 July 2018 at 03:48, Michal Simek <michal.simek at xilinx.com> wrote:
>
> On 25.7.2018 08:31, Chee, Tien Fong wrote:
> > On Wed, 2018-07-18 at 16:48 +0200, Michal Simek wrote:
> >> On 6.7.2018 10:28, tien.fong.chee at intel.com wrote:
> >>>
> >>> From: Tien Fong Chee <tien.fong.chee at intel.com>
> >>>
[...]

> >>
> >> Also that DT binding is quite weird and I don't think you will get
> >> ACK
> >> for this from device tree community at all. I think that calling via
> >> platdata and avoid DT nodes would be better way to go.
> > Why do you think DT binding is weird? The DT is designed based on Simon
> > proposal, and i believe following the rules in DTS spec.
> > There are some DT benefits with current design, i think someone may be
> > maintainer need to made the final decision on the design.
>
> It is software configuration in file which should mostly describe
> hardware and state for hardware configuration.
>
> Your fs_loader node is purely describe sw configuration which shouldn't
> be here.
> You have there run time configuration via variables. I think using only
> this way is enough. Default variables will match what you would want to
> add to DT.

I think DT makes sense in the U-Boot context.

We don't have a user space to handle policy decisions, and the
'chosen' node is a good place to configure these common features.

While you can argue that the partition or filesystem where an image
comes from is a software config, it is something that has to be
configured. It has impact on hardware too, since the FPGA has to get
its firmware from somewhere. We use the chosen node to specify the
UART to use, and this is no different. Again, we don't have user-space
config files in U-Boot.

This argument comes up from time to time and I'd really like to put it
to bed for U-Boot. I understand that Linux has its own approach and
rules, but in some cases they serve U-Boot poorly.

Regards,
Simon