[PATCH v6 09/25] arm: xenguest_arm64: Add a fake devicetree file

[Simon Glass]

Hi François,

On Thu, 2 Dec 2021 at 11:44, François Ozog <francois.ozog at linaro.org> wrote:
>
> Hi Simon
>
> On Thu, 2 Dec 2021 at 19:29, Simon Glass <sjg at chromium.org> wrote:
>>
>> Hi François,
>>
>> On Thu, 2 Dec 2021 at 11:17, François Ozog <francois.ozog at linaro.org> wrote:
>> >
>> > Hi Simon
>> >
>> > On Thu, 2 Dec 2021 at 19:05, Simon Glass <sjg at chromium.org> wrote:
>> >>
>> >> Hi Tom,
>> >>
>> >> On Thu, 2 Dec 2021 at 10:56, Tom Rini <trini at konsulko.com> wrote:
>> >> >
>> >> > On Thu, Dec 02, 2021 at 05:40:46PM +0000, Oleksandr Andrushchenko wrote:
>> >> > > Hi, Simon!
>> >> > >
>> >> > > Sorry for being late to the party
>> >> > >
>> >> > > On 02.12.21 17:59, Simon Glass wrote:
>> >> > > > Add an empty file to prevent build errors when building with
>> >> > > > CONFIG_OF_SEPARATE enabled.
>> >> > > >
>> >> > > > The build instructions in U-Boot do not provide enough detail to build a
>> >> > > > useful devicetree, unfortunately.
>> >> > > Xen guest doesn't use any built-in device trees as the guest's device tree is provided
>> >> > > by the Xen hypervisor itself and is generated at the virtual machine creation time: it is
>> >> > > populated with memory size, number of CPUs etc. based on [1].
>> >> > > So, even if we provide some device tree here it must not be used by U-boot at
>> >> > > the end of the day. Thus, it might be a reasonable solution to provide an empty device
>> >> > > tree as you do, but put a comment that it is not used.
>> >> >
>> >> > So another example of why this series is taking things in the wrong
>> >> > direction.
>> >>
>> >> Why?
>> >
>> > I only had that comment in mind: "there is none so deaf as he who will not hear."
>>
>> Hey, stop the pile-on. It's not useful.
>>
>> I've guided U-Boot's use of devicetree for 10 years successfully. The
>> current state is a mess and I just to straighten it out.
>>
> I admire your talent and knowledge.
> I know you are 99,99% of the time correct and spot on for your comments in many meetings we were attending.
> When you questioned a number of points I made, I first tried to understand what I got wrong because you said it.
> And you were right ;-)
> For this topic, I made every effort to come to your position, but definitively can't.

Thank you. I think this will come together in a few years when
devicetree is sorted out in U-Boot and Binman is more widely used.

For this series, if and when it is applied, I predict:
- it will not cause any confusion
- it will aid development
- it will help with discoverability, pressuring people to explain how
to build for their systems
- it will be a good basis for future work (we have a long list)
- everyone will wonder what the fuss was about

Here is the commit that introduced OF_PRIOR_STAGE. It attracted no
such push-back.

commit 894c3ad27fa940beb7fdc07d01dcfe81c03d0481
Author: Thomas Fitzsimmons <fitzsim at fitzsim.org>
Date:   Fri Jun 8 17:59:45 2018 -0400

    board: arm: Add support for Broadcom BCM7445

    Add support for loading U-Boot on the Broadcom 7445 SoC.  This port
    assumes Broadcom's BOLT bootloader is acting as the second stage
    bootloader, and U-Boot is acting as the third stage bootloader, loaded
    as an ELF program by BOLT.

    Signed-off-by: Thomas Fitzsimmons <fitzsim at fitzsim.org>
    Cc: Stefan Roese <sr at denx.de>
    Cc: Tom Rini <trini at konsulko.com>
    Cc: Florian Fainelli <f.fainelli at gmail.com>

Regards,
Simon