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On a Samsung ARM Chromebook, could nv-uboot easily boot to stock linux k


From: Subharo Bhikkhu
Subject: On a Samsung ARM Chromebook, could nv-uboot easily boot to stock linux kernels, by way of ARM-GRUB?
Date: Wed, 1 Jan 2014 09:48:41 -0500

Hello,

Firstly, huge props to the Debian ARM gods who have done so much wonderful work so far, especially Marcin Juszkiewicz, Olof Johansson, Andrew Wafaa, and Jay Lee.

I have a Samsung ARM Cromebook.  I'm running Chrubuntu 13.04 in the internal 16GB eMMC.  The security updates are about to run out (damned 9-month support period!).  A simple "do-release-upgrade" will lead to a non-functioning x.org:
http://ubuntuforums.org/showthread.php?t=2181898

I'm not excited to freshly install Chrubuntu 13.10 either, as the security updates will run out too quickly as well.  I want something that will last at least a couple of years!

So I'm interested in a fresh install of Debian, to get (among other things) a much longer period of security updates.  The best page I've found on this so far is:  "InstallingDebianOn Samsung ARMChromebook":
https://wiki.debian.org/InstallingDebianOn/Samsung/ARMChromebook
...but the current problem is that one cannot boot from a stock linux kernel.  One currently must "borrow" the ChromeOS kernel, and "sign" it.  I would prefer to have no ongoing dependency on ChromeOS if I can help it, and have a Chromebook completely free of ChromeOS altogether.

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

  "Three partitions are created on the disk. In time, the intention is that these be used for:
   - a copy of nv-uboot that is chainloaded by the standard firmware,
   - a /boot filesystem containing the standard (non-ChromeOS) kernel, read by nv-uboot,
   - the root filesystem.

  Currently nv-uboot is *not* used, and so the arrangement is:
   - a copy of the ChromeOS kernel that is loaded by the standard firmware,
   - a /boot filesystem that is used only to contain the ChromeOS kernel (which is not used during booting, just during the preparation of the previous partition),
   - the root filesystem."

Also helpful: "Appendix A: Using nv-U-Boot on the Samsung ARM Chromebook":
http://www.chromium.org/chromium-os/u-boot-porting-guide/using-nv-u-boot-on-the-samsung-arm-chromebook
...but nv-U-Boot has several disadvantages listed there (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/
Can anybody comment on the feasibility of the following idea? 

What if nv-u-boot was used simply to boot to ARM-GRUB, and then GRUB in turn was used to boot from a "normal-looking" selection of stock linux kernels (along with rescue modes, etc.)?  For example, GRUB stage 1 (and/or stage 1.5) could be installed to a small GPT partition (instead of the MBR, as is done on pre-UEFI PC's).  Then GRUB stage 1 (or 1.5) could in turn boot from a GRUB stage 2, located in a small dedicated /boot ext2 partition (stored along with stock linux kernels, in the way that is familiar to us on PC's).  Or maybe GRUB stage 1 (or 1.5) could boot directly to stock linux kernels on an ext4 root partition (with no dedicated /boot partition). 

It might sound cumbersome to effectively have 2 boot-loaders, but it might make this whole situation much simpler, as there's *a lot* more GRUB expertise out there (than there is around nv-u-boot).  I'm thinking about potentially saving lots of time and manpower, and not caring about squandering a few tens of MB and an unused GPT partition in my internal 16GB eMMC.

Remember the joke "Internet Explorer is a good Web Browser, for installing a better Web Browser"?  Well, perhaps a corollary joke might become "nv-uboot is a good boot-loader, for booting to a better bootloader".  ;)

Note: I'm aware of the this tutorial, to install Debian Jesse:
"Replacing Chrome OS with Debian Jessie on the Samsung Series 3 Chromebook":
http://www.neowin.net/forum/topic/1173005-replacing-chrome-os-with-debian-jessie-on-the-samsung-series-3-chromebook/
...however there are a lot of custom-compiled packages packaged by the author ("Karl L.") that one would need to place a great deal of trust on (both now, and in the future, especially considering the ongoing need for timely security updates).  I'd like to rely on something much more "official"-looking (as posted on https://wiki.debian.org/InstallingDebianOn/Samsung/ARMChromebook), whereby all ongoing security updates would ideally "just work" like any regular Debian install.

Any constructive feedback would be most appreciated (especially comments on the maturity of ARM-GRUB, or any "magical" GRUB options and configurations that might help on the Samsung ARM Chromebook).

Cheers,
Subharo

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