On Mon, Mar 18, 2019 at 12:31:32PM -0600, Stephen Warren wrote:
On 3/8/19 1:10 PM, Thierry Reding wrote:
From: Thierry Reding treding@nvidia.com
In order to support chainloading of U-Boot by an earlier bootloader, make sure the binary is position independent, so that the earlier boot- loader can relocate it if necessary.
Why not enable this for all 64-bit Tegra? They're all booted the exact same way at least with recent L4T builds.
Yeah, I think that would make sense.
Also, U-Boot is typically linked to the address that cboot loads it to, and cboot typically always loads to precisely that address. I'm not sure why this patch is required.
I encountered this issue when I was trying to chainload U-Boot from cboot on Jetson TX1. It seems like your above comment is no longer true, though I suppose that could just mean that the link address for U-Boot has become stale?
That said, it don't think it harms anything, so I'm fine with it being applied.
I suppose there's a bit of extra code to do the indirect jumps, but overall U-Boot seems to work well and not noticeably slower if this is enabled. Might be nice for extra flexibility and to avoid any surprises if we ever end up loading U-Boot to a location other than where it was liked to.
My understanding is that this could happen on Tegra186 if cboot detects bad memory blocks in the area where U-Boot was meant to be loaded to. I guess this doesn't apply to earlier chips, but perhaps it's good to have it there for consistency anyway.
Thierry