Re: [PATCH RFC] arm64: tegra: Add reserved-memory node for P3450

[Aaron Kling]

On Thu, Jul 3, 2025 at 11:24 AM Nicolas Chauvet <kwizart@xxxxxxxxx> wrote:
>
> Le jeu. 3 juil. 2025 à 13:00, Thierry Reding
> <thierry.reding@xxxxxxxxx> a écrit :
> >
> > On Mon, May 26, 2025 at 02:07:35PM -0500, Aaron Kling wrote:
> > > On Mon, May 26, 2025 at 2:06 PM Aaron Kling via B4 Relay
> > > <devnull+webgeek1234.gmail.com@xxxxxxxxxx> wrote:
> > > >
> > > > From: Aaron Kling <webgeek1234@xxxxxxxxx>
> > > >
> > > > The Tegra210 L4T bootloader ram training will corrupt the in-ram kernel
> > > > dt if no reserved-memory node exists. This prevents said bootloader from
> > > > being able to boot a kernel without this node, unless a chainloaded
> > > > bootloader loads the dt. Add the node to eliminate the requirement for
> > > > extra boot stages.
>
> Is there any particular reason why this applies on jetson-nano but not
> jetson-tx1 (or any other l4t based boards ?)

I answered that in my first reply to this patch. This does also apply
to p2371-2180, aka the Jetson TX1 devkit, but I don't need it for my
use case because it is supported by the android bootloader. To my
knowledge, there are not any other supported t210 devices that use the
l4t bootloader. And this is not a problem on other archs. If there's a
desire, I can replicate this to p2371-2180 and send a v2 without the
rfc tag. Probably better to do so for consistency anyways.

> I wonder if it would be enough to boot an upstream kernel with the l4t
> bootloader (and no chainloaded upstream u-boot) as I cannot do the
> other way for some reason (using fedora based upstream u-boot cannot
> boot downstream l4t kernel anymore)

Mmm, I'm not sure. I can boot a mainline kernel on the l4t bootloader
without u-boot after this patch. But my use case is android. I've also
booted a simple busybox initramfs to do non-android verification of
changes. But I've not booted a full Linux distro.

Aaron