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.

Is there any other alternative I'm not seeing? Having the kernel
suddenly become incompatible with any currently extant bootloader when I
enable CONFIG_MULTIPLATFORM doesn't seem like a great idea.

I *think* it's ok to deprecate fastboot on older devices. AFAIK, the in-kernel 
supported boards all have u-boot support already.

Marc