On a Samsung ARM Chromebook, could nv-uboot easily boot to stock linux kernels, by way of ARM-GRUB?

[Held Bier]

Hi, Subharo

> one cannot boot from a stock linux kernel

One can, but Samsung ARM Chromebook is not fully supported by mainline
kernel. At least you'll miss wi-fi.You have few options here: take a
mainline kernel and apply all the fixes that you need from kernel tree
at Chromium project, or search if someone else have already done that.
That will be helpful for the whole Linux community, if you or someone
else will try to push needed fixes upstream.

> One currently must "borrow" the ChromeOS kernel

It's the kernel with best support for this machine. If you're trying
to avoid using Google's blobs, you may take the tree code from
https://chromium.googlesource.com/ instead
(chromiumos/third_party/kernel -b release-R31-4731.B is what stable
Chrome OS uses atm) instead, which you're free to investigate prior
usage (an old building guide
http://people.redhat.com/wcohen/chromebook/chrome_kernel.txt is mostly
right).
You'll still need few proprietary components to get full hw support:
1) Mali GPU userland driver;
2) Wi-Fi firmware;
3) HW videocodec firmware (highly optional).

> and "sign" it

Besides booting of dev-keys signed images you may choose other
options: 1) replacing of stock u-boot with nv-u-boot (cracking of
Chromebook required); 2) setting a chain-loaded nv-u-boot.
You may then boot usual non-u-boot images with help of kexec (like
Luke suggested).

> The Debian folks are currently stuck on how to boot a stock linux kernel from 
> nv-u-boot

I doubt they're stuck. The wiki way is just the most easy and fast. I
had no problems in booting Linux from nv-u-boot, and there is nothing
distro-special about it. For Google's nv-u-boot you're just making a
combined image of exynos5250 device tree and your kernel in form of
zImage, and then booting it.

> as compared to, say, the much more mature and familiar GRUB
> There is a version of GRUB for ARM: http://sourceforge.net/projects/arm-grub/

I'm not sure that ARM version is that mature and stable as it's x86
counterpart. I've also never heard of it being used by default on any
commercial ARM device. Redboot and U-boot are mostly used by the ARM
hardware you'll find on market, and they're used to directly boot into
the OS.
You're seem to be a man of your own habits. GRUB and other 2-nd stage
loaders are helpful on PC, where BIOS (and now EFI) knows little about
how to boot into OS. Contrary, on ARM, the 1-nd stage loaders which
are a firmware at same time are usually used, and there is easier to
learn it's ecosystem, than try to put an unneeded middleware.