Qi - why only 3 partitions on SD card?

[Dave Ball]

Dr. H. Nikolaus Schaller wrote:
> What I wonder is why nobody did fix u-boot if it had problems with  
> bigger kernels.
>   
I'm just a bystander here, but from what I understood this wasn't the 
reason Qi was started.

u-boot is an entire environment that needs drivers for a lot of the 
hardware (usb, graphics, pmu, etc.) all of which end up duplicated in 
the Linux kernel.  The u-boot philosophy (of an entire environment 
supporting DFU and a boot menu) implies that those drivers have to be 
maintained in two places (u-boot and kernel) which cases pain, and 
inevitably results in u-boot being slower to boot.

Qi starts with a completely different philosophy - that the bootlooder 
should do as little as possible, and that it should need to know as 
little as possible about the hardware.  In terms of intent, it's closer 
to the coreboot project than it is to u-boot.  You really couldn't 
achieve this [separation of bootloader & device drivers] with u-boot, 
which is why the separate Qi project was formed instead of continuing to 
evolve u-boot.

So what you _can't_ do inside Qi is have a graphical boot menu, or 
support dfu - because Qi doesn't know how to talk to the hardware.  What 
you _can_ do is construct a mini Linux environment that provides a boot 
menu / usb-dfu, and is booted by Qi in the normal way.  This would place 
those tools in regular Linux userspace, i.e. much more accessible to 
regular non kernel / bootloader hackers.  This could be the default or 
secondary boot option - provide a boot menu and then chainload the 
desired final Linux environment.

There's a philosophical difference between the two projects, and I think 
Qi's approach is much better suited to this kind of hardware, than 
u-boot could ever be (with trunk, or with the existing gripes resolved). 

> But you can only influence the future but never change the history...
>   

Wise words! :-)  Imho our time would be better spent building this 
mini-environment (which would probably be best constructed in initrd as 
Paul mentioned) than returning to u-boot.

Any takers?


Dave