Re: [PATCH v2 0/3] arm64: dts: rockchip: minimal support for Pre-ICT tester adapter for RK3588 Jaguar + add overlay tests

[Niklas Cassel <cassel@kernel.org>]

On Thu, Jan 23, 2025 at 03:13:01PM +0100, Heiko Stübner wrote:
> Am Mittwoch, 22. Januar 2025, 17:12:26 CET schrieb Niklas Cassel:
> > On Wed, Jan 22, 2025 at 04:38:16PM +0100, Quentin Schulz wrote:
> > > So essentially, if SPL_ATF_NO_PLATFORM_PARAM is selected (the default for
> > > RK356x, RK3588, forced on on RK3308, enabled for the majority of RK3399
> > > boards, enabled for all RK3328 boards) the DT won't be passed to TF-A so no
> > > issue in terms of size on that side.
> > > If it is not selected, for TF-A < 2.4 (released 20201117, 4 years ago), a
> > > DTB bigger than 64KiB will crash TF-A.
> > > If it is not selected, for TF-A >= 2.4, a DTB bigger than 128KiB will result
> > > in TF-A not being able to read the DTB (for Rockchip, that means not being
> > > able to derive the UART settings (controller and baudrate) to use, and will
> > > use the compile-time default instead).
> > 
> > Not everyone is using binary blobs from Rockchip.
> > On my rock5b (rk3588), I'm building the bootloader using buildroot,
> > which is using upstream TrustedFirmware-A (v2.12).
> > 
> > 
> > > In short, I don't know where to go with that additional piece of
> > > information, but this is a bit bigger than simply moving things around and
> > > adding compile-time tests for overlay application.
> > 
> > This is significant information indeed.
> 
> I guess the question is, can this hurt existing devices?
> 
> As Quentin mentioned, this only affects DTs that get handed over from
> U-Boot to TF-A (and maybe OP-TEE).
> 
> So the whole range of things loading their DT from extlinux.conf or
> whatever are not really affected.
> 
> 
> DTs U-Boot can hand over are 2 types,
> (1) built from within u-boot and
> (2) stored somewhere centrally (SPI flash).
> 
> 
> Case (1) is again not affected, as U-Boot (and other bootloaders) may
> very well sync the DTS files, but generally not the build-system, so if
> U-Boot (or any other bootloader) creates DTBs with symbols is completely
> their own choice.
> 
> 
> And for case (2) I see the manufacturer being responsible. Having the DT
> in central storage makes it somewhat part of a "bios"-level in the hirarchy
> and the general guarantee is that new software _will work_ with older DTs,
> but the other way around is more a nice to have (old SW with new DTB).
> 
> So if some manufacturer has a centrally located DTB this does not matter
> until they upgrade, and when that happens I do expect testing to happen
> at the manufacturers side, before rolling out a "bios update"

Personally, I'm all for letting the kernel build the DTBs with symbols.

(I have a patch that I keep rebasing on my tree only for that purpose.
Sure, I could modify my build scripts to build the DTB separately,
but with this patch, I do not need to do anything since the kernel
builds the DTBs already.)

Other platforms, e.g. TI already build many boards with symbols:
https://github.com/torvalds/linux/blob/v6.13/arch/arm64/boot/dts/ti/Makefile#L242-L261


You seems to have been against enabling symbols before:
https://lore.kernel.org/linux-rockchip/171941553475.921128.9467465539299233735.b4-ty@sntech.de/
https://lore.kernel.org/linux-rockchip/1952472.6tgchFWduM@diego/

But if you have changed you mind, and you are no longer concerned about
doing so, then in my own self-interest I'm all for it :)


Kind regards,
Niklas