Acer Chromebook 13 - can not access legacy BIOS

[Luís de Sousa]

Dear all,

I have been trying to boot various desktop Linux distributions from a USB stick on an Acer Chromebook 13 (CB5-311). I have set the dev_boot_usb and dev_boot_legacy flags to 1 but when I press Ctrl+L at the boot screen I only get a beep and it follows on to boot ChromeOS regularly.

A similar problem is reported in a old thread regarding the Chromebook Pixel:

https://groups.google.com/a/chromium.org/forum/?hl=en#!topic/chromium-os-discuss/zOB3zcSL8rk

The solution for the Pixel is a re-flash of the legacy BIOS, a method that is not reported in the Wiki:

http://dev.chromium.org/chromium-os/developer-information-for-chrome-os-devices/chromebook-pixel#TOC-Legacy-Boot-Doesn-t-Work

Would it be safe to run this same fix on the Chromebook 13? And would it solve the problem?

Thank you.

[Sonny Rao]

I believe Acer Chromebook 13 uses the Tegra K1 processor, and ARM cpu
which doesn't support SEA BIOS like x86 Chromebooks. So that method
would not work.

I'm not sure if anyone has made any sort of a legacy payload for that
platform like a u-boot image but a quick search didn't show me
anything.
That said, it's still possible to boot another Linux based OS -- see
this page for example:
http://www.vctlabs.com/posts/2015/Jan/22/tegra_chromebook_hack/

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[Luís de Sousa]

Thank you Sonny for the reply.

That method you refer is an adaptation for Gentoo of an old script published by Jay Lee 3 years ago:

http://chromeos-cr48.blogspot.lu/2012/12/so-you-want-chrubuntu-on-external-drive.html

I have tried it before and unfortunately it fails on this particular Chromebook (as it seems to fail with other models).

In any case, the information that the Tegra K1 does not support the legacy BIOS is capital. I believe this means booting from a USB is not possible in this model.

Thank you.

[Mike Frysinger]

as Sunny said, this is an ARM cpu, so there is no "legacy boot" support.  that simply means there is no SeaBIOS (since that is x86-only).

it does *not* mean you can't boot from USB.  you can boot CrOS formatted images (gpt+vboot kernels really) from USB just fine.

the links you posted all talked about the Pixel which is not your device.  in general you should focus on documentation that is either specific to your device, or applies to all CrOS devices.  in your case, this page applies:

http://dev.chromium.org/chromium-os/developer-information-for-chrome-os-devices/acer-cb5-311-chromebook-13

-mike

[Luís de Sousa]

Thank you for the link Mike. So far this forum is the only place where I actually get replies to my issues.

Let me then put this in a straight way: can I boot a desktop Linux system from a USB on the Tegra K1? If yes, how?

I already tried the Ctrl+U key combination with a bootable USB and the result is almost the same as with Ctrl+L (the beep tone is different).

Thank you.

[Luís de Sousa]

My apologies for the spam, this is actually clearly stated in the development page:

"Note: Only CrOS formatted images will boot via USB. Other Linux distros will not work."

Thank you once again.

[Mike Frysinger]

it is possible to take a distro kernel and format it in the way the CrOS bootloader expects, but i'm not sure we have any easy docs that cover this.  so your best bet right now would probably be to just use Crouton.

-mike

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