Multi-platform, and secure-only ARM errata workarounds

[Nicolas Pitre]

On Tue, 26 Feb 2013, Stephen Warren wrote:

> 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.

The bootloader should grow some ability to script those errata 
workarounds.  Most bootloaders already have memory read and write 
commands, so only CP access is missing.


Nicolas