[U-Boot] [PATCH] p2371-2180: Build position independent binary

[Stephen Warren]

On 3/20/19 4:27 AM, Thierry Reding wrote:
> On Tue, Mar 19, 2019 at 11:05:43AM -0600, Stephen Warren wrote:
>> On 3/19/19 6:12 AM, Thierry Reding wrote:
>>> 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 at 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?
>>
>> Looks like the upstream CONFIG_SYS_TEXT_BASE is indeed stale relative to the
>> latest L4T builds:
>>
>> Upstream:
>> Jetson TX1: CONFIG_SYS_TEXT_BASE=0x80110000
>> Jetson TX2: CONFIG_SYS_TEXT_BASE=0x80080000
>>
>> L4T r32.1:
>> Jetson TX1: #define CONFIG_SYS_TEXT_BASE    0x80080000
>> Jetson TX2: #define CONFIG_SYS_TEXT_BASE    0x80080000
> 
> Okay, let me fix that up while at it. I think the 0x80110000 text base
> was something that we cargo-culted from 32-bit ARM boards. I vaguely
> recall that this might have been related to the SPL split in some way,
> but I can't find anything to corroborate that.

I believe it was accurate for the first L4T release to support Tegra210, 
which chain-loaded U-Boot from nvtboot-cpu rather than chain-loading it 
from cboot. But, I could be wrong.