Subject: Multi-platform, and secure-only ARM errata workarounds

From: [email-masked] (Stephen Warren)
Date: Tue, 26 Feb 2013 09:39:15 -0700

On 02/26/2013 02:36 AM, Marc Dietrich wrote:
> Stephen,
> 
> Am Montag, 25. Februar 2013, 16:47:38 schrieb Stephen Warren:
>> I'm looking into enabling CONFIG_MULTIPLATFORM on Tegra for 3.10, and
>> the main blocking issue is due to commit 62e4d35 "ARM: 7609/1: disable
>> errata work-arounds which access secure registers". Various Tegra
>> versions need 3 of those workarounds, and our bootloader doesn't
>> implement them (at the least, upstream U-Boot; not sure about our
>> downstream code, but I'm fairly sure given the lack of any feedback I
>> got in the bug I filed to implement them).
>>
>> Now, I can easily add those 3 errata workarounds to U-Boot, but that
>> will require people to reflash their bootloader. This is probably
>> acceptable for development/reference boards (although I'm sure people
>> will find it annoying) but for re-purposed production boards (such as
>> the Toshiba AC100 or various tablets) it will be impossible to update
>> the factory bootloader. Switching to upstream U-Boot would currently
>> lose some functionality, and significantly affect people's boot flow, so
>> is likely unacceptable.
> 
> personally, I have no problem to require a certain u-boot version for a given 
> kernel. From a distro point of view, you will likely update the 
> bootloader/kernel on a distro update anyway.

So a distro will certainly update the kernel.

But updating a bootloader would be very unusual, I believe.

Also, I hope that upstream U-Boot is never going to support the bizarre
"Tegra partition table" cruft that our "fastboot" bootloader supports,
so you'll end up completely re-programming the flash (BCT, bootloader,
partition table, all filesystems) if you want to switch to U-Boot. That
seems like a fair chunk for the installer to own, but I guess if you're
comfortable with doing that, I won't complain.