please don't switch to kexec (was Re: R70/R71 on debug v3 board ?)

Werner Almesberger werner at
Mon Feb 11 13:32:11 CET 2008

Harald Welte wrote:
> Do you realize that you are just scrapping the ability to 
> boot any different OS on the device?

I wonder how you jump to this conclusion. It's not as if there'd be
some "secret trusted BIOS" that enforces signed binaries or such.

> By switching to kexec, you virtually remove that ability.  Yes, people
> can still replace the linux kernel with a bootloader, but it is _MUCH_
> harder since you have to do all the low-leve setup such as GPIO
> configuration, etc. again.  A common bootloader for PLL/GPIO init helps
> a lot in that regard.

They'll have to port tons of drivers anyway. I doubt a few GPIOs, would
break their back :-) If they're really having too hard a time to bring
up their kernel, they could even take the old u-boot code and run that
first. Or just bring up Linux and dump the registers they're interested

Yes, I can see how it might (*) make the effort of porting a non-Linux
system marginally easier. However, I don't see any sensible relation
between this and the drain of resources keeping u-boot around means
to us.

(*) Actually, if I had to start from scratch, I'd probably just do all
    the initialization myself anyway, so that it's done by code I
    fully control.

I can understand your decision for choosing u-boot when there was no
code at all that ran on our platform. But now we're in a much better
situation, and we can move on and use tools that fit our needs better.

> Also, dual-booting different OS's is no longer possible.

We obviously want to be able to choose kernels. So any other OS would
just be another binary that you load and jump to. No discrimination
there. (BTW, you're already talking about the next step, which would
be NAND booting. For now, we're just thinking about NOR.)

- Werner

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