Problem with U-boot | Configuration Signature not being checked while booting

[Simon Glass]

Hi François,

On Wed, 15 Sept 2021 at 04:26, François Ozog <francois.ozog at linaro.org> wrote:
>
>
>
> Le mer. 15 sept. 2021 à 12:13, Simon Glass <sjg at chromium.org> a écrit :
>>
>> Hi Mark,
>>
>> On Sat, 11 Sept 2021 at 13:18, Mark Kettenis <mark.kettenis at xs4all.nl> wrote:
>> >
>> > > From: Moiz Imtiaz <moizimtiaz1 at gmail.com>
>> > > Date: Sat, 11 Sep 2021 23:19:05 +0500
>> > >
>> > > Hi Simon,
>> > >
>> > > Thanks for the reply.  I already followed the steps mentioned in
>> > > "doc/uImage.FIT/beaglebone_vboot.txt".
>> > >
>> > > >I wonder if rpi is not using the devicetree compiled with U-Boot, but
>> > > instead one provided by the earlier-stage firmware?
>> > >
>> > > Not sure, but seems like this is the case. I checked and there isn't any
>> > > dtb or dts for rpi4 (bcm2711-rpi-4-b) in arc/arm/dts in u-boot. I tried to
>> > > add the dtb and other dts dtsi
>> > > <https://github.com/raspberrypi/linux/tree/rpi-5.10.y/arch/arm64/boot/dts/broadcom>files
>> > > from the raspberry pi Linux and compile them with CONFIG_OF_SEPARATE and
>> > > CONFIG_OF_EMBED (one at a time) *but it couldn't even boot the U-Boot and
>> > > it would just give a blank screen*. I wonder why there isn't any device
>> > > tree in the U-boot repo for RPI4. Is U-boot control FDT not supported by
>> > > RPI4?
>> >
>> > The issue with the rpi4 is that the addresses of devices move around
>> > based on the version of the Raspberry Pi firmware you're using.  And
>> > possibly on the amount of memory on the board as well.  So U-Boot
>> > pretty much has to use the device tree passed by the firmware since
>> > the device tree in the U-Boot tree would be wrong for many
>> > combinations of firmware and hardware.
>> >
>> > Simon, this sort of thing is exactly the reason why I think the idea
>> > of having all U-Boot configuration information in a single device tree
>> > with the hardware description doesn't work everywhere.
>>
>> From my reading of this thread, it rather reinforces the need to
>> provide a way to give U-Boot the config it needs, in the devicetree.
>>
>> It seems that rpi is actually OK in this regard. If you think about
>> it, it would be pretty hopeless if first-stage firmware assumed that
>> it could provide a devicetree to whatever is next. For example, if
>> U-Boot evolves to support more devices, they could not be supported.
>> If UEFI is used, the devicetree would have no effect, since it doesn't
>> support devicetree.
>
> Please use EDK2 when you refer to it and not by the interface it implements. And even if we read “If EDK2 is used” this is false as Socionext has a platform that can select ACPI or DT for its EDK2 implementation.

OK I will try to remember to use 'EDK2' to describe a UEFI
implementation. Since all the other UEFI implementations are
closed-source(?) I suppose it is the only one that is relevant here.
Not that EDK2 actually supports very many boards, so far as I can tell
from the source tree.

I recall people complaining about libfdt being needed in EDK2 (I
assume, perhaps it was some other UEFI?) Are you saying that EDK2 can
use devicetree for its configuration? If not, thenI think you
misunderstood my point.

> TF-A has fat less drivers than U-Boot. There is no problem in having a “verified” platform DT stored in BL33_CONFIG part of a FIP, verified by TFa and handed over by U-Boot to OS.
> That can be the same thing in RPI4 case or FPGA boards.
>>

OK. I think you are saying that we can use TF-A on rpi and have it
provide a suitable devicetree for U-Boot. That's fine. However it
happens is fine. It just needs to support the features U-Boot
supports, not provide a partial devicetree forcing U-Boot to put its
config elsewhere.


>>
>>
>> So perhaps the only remaining issue is with qemu on ARM / Risc-V?

Regards,
Simon