How to load a new kernel on ChromeOS

[Paco GB]

Hi,

I'm new in ChromiumOS dev, first thing i tried to do is to compile a new version of the kernel and try to load it in ChromeOs.

I did manage to download, configure and compile the Kernel using crouton, but know i don't know how to load it.

After reading the presentation of "Verified boot"

https://docs.google.com/presentation/d/1HHf_0nKrceQr_NQYGMpVlYTIYF8ky-eNxP7W5Lxw94Y/present?slide=id.g3891f5dfb_0132

In the slide  21 I see that in developer mode it is possible to load a different kernel without modifying the firmware. But I'm not really sure how?

Do you know any documentation or reference where i can look to? 

Thanks, 

[Christopher Friedt]

That's a really good question... I recently found that
CONFIG_HID_MAGICMOUSE is not enabled for the kernel in my Asus
ChromeBit, and imagine that it could possibly take years for the CrOS
team to change that, just so that I can scroll with my mouse.

[Steev Klimaszewski]

Or, you could create a pull request enabling the option and explaining it and submitting it to their codereview.  Which is what I've done on occasions where I've wanted an option enabled.  It did not take years, it simply took me doing the work and explaining why it was needed.  Doing the work instead of waiting for someone on the team to have the same hardware and desires as you tends to get things done quicker. 

[Dmitry Torokhov]

Hmm, we do have this driver enabled on most of our builds, so there
shouldn't be issues enabling it on chromebits as well:

(cr) dtor@dtor-ws ~/trunk/src/third_party/kernel $ grep -r MAGICM v*/chromeos/
v3.10/chromeos/config/base.config:CONFIG_HID_MAGICMOUSE=m
v3.14/chromeos/config/mips/common.config:CONFIG_HID_MAGICMOUSE=m
v3.14/chromeos/config/i386/common.config:CONFIG_HID_MAGICMOUSE=m
v3.14/chromeos/config/arm64/common.config:CONFIG_HID_MAGICMOUSE=m
v3.14/chromeos/config/armel/chromiumos-rockchip.flavour.config:CONFIG_HID_MAGICMOUSE=m
v3.14/chromeos/config/armel/chromiumos-cygnus.flavour.config:#
CONFIG_HID_MAGICMOUSE is not set
v3.14/chromeos/config/armel/chromiumos-arm.flavour.config:CONFIG_HID_MAGICMOUSE=m
v3.14/chromeos/config/x86_64/common.config:CONFIG_HID_MAGICMOUSE=m
v3.18/chromeos/config/mips/common.config:CONFIG_HID_MAGICMOUSE=m
v3.18/chromeos/config/i386/common.config:CONFIG_HID_MAGICMOUSE=m
v3.18/chromeos/config/arm64/common.config:CONFIG_HID_MAGICMOUSE=m
v3.18/chromeos/config/armel/chromiumos-ipq40xx.flavour.config:#
CONFIG_HID_MAGICMOUSE is not set
v3.18/chromeos/config/armel/chromiumos-arm.flavour.config:CONFIG_HID_MAGICMOUSE=m
v3.18/chromeos/config/armel/chromiumos-armada38x.flavour.config:#
CONFIG_HID_MAGICMOUSE is not set
v3.18/chromeos/config/x86_64/common.config:CONFIG_HID_MAGICMOUSE=m
v3.8/chromeos/config/base.config:CONFIG_HID_MAGICMOUSE=m
v4.4/chromeos/config/base.config:CONFIG_HID_MAGICMOUSE=m

Hmm, Chromebits are Rockchip devices with 3.14 kernel, so they should
already have magicmouse enabled (see
v3.14/chromeos/config/armel/chromiumos-rockchip.flavour.config). Could
it be that you need some other driver? Or maybe support for your
version of device was added to a newer kernel?

Thanks,
Dmitry

[Christopher Friedt]

On Thu, Dec 29, 2016 at 1:42 PM, Dmitry Torokhov <dt...@chromium.org> wrote:
> Hmm, we do have this driver enabled on most of our builds, so there
> shouldn't be issues enabling it on chromebits as well:
>
> (cr) dtor@dtor-ws ~/trunk/src/third_party/kernel $ grep -r MAGICM v*/chromeos/

> v3.14/chromeos/config/armel/chromiumos-rockchip.flavour.config:CONFIG_HID_MAGICMOUSE=m

> Hmm, Chromebits are Rockchip devices with 3.14 kernel, so they should
> already have magicmouse enabled (see
> v3.14/chromeos/config/armel/chromiumos-rockchip.flavour.config). Could
> it be that you need some other driver? Or maybe support for your
> version of device was added to a newer kernel?

Hmm... I have a Magic Mouse 2 (which is the bluetooth version). After
looking in drivers/hid-magicmouse.c, it looked as though it was part
of that driver. None of the scrolling (vert / horiz) or any other
mouse gestures seem to do anything in CrOS, so I assumed the module
was not loaded.

[Christopher Friedt]

This might be the issue.

https://goo.gl/SJUhTi

Module parameter 'emulate_scroll_wheel' is not set by default.

©

Sent from my Android

[Dmitry Torokhov]

The parameter is on by default:

drivers/hid/hid-magicmouse.c:static bool emulate_scroll_wheel = true;

On Thu, Dec 29, 2016 at 12:06 PM, Christopher Friedt

[Christopher Friedt]

Weird.

Does not scroll at all.

©

Sent from my Android

[Dmitry Torokhov]

Well, is it the original Magic mouse or a newer one? What is the
VID/PID? Do you have it working properly on a generic Linux
distribution?

Please collect the data and open a bug on crosbug.com.

Thanks,
Dmitry


On Thu, Dec 29, 2016 at 12:15 PM, Christopher Friedt

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[Justin S]

I'm not sure but this get threadjacked? The original post was asking if there is a how-to on loading new kernels. Since the second post this has been all about Magic Mouse scrolling support, or whatever. I've been lurking for a few weeks and he original question is the reason I joined this group in the first place. Is there a decent how-to of sorts? Thanks!

[Prathmesh Prabhu Chromium]

Looping back to that question, if you're in developer mode, you don't need to change the firmware to boot into an image built at your workstation. This is described in detail at http://dev.chromium.org/chromium-os/developer-guide#TOC-Installing-Chromium-OS-on-your-Device

Of course, you can build in any kernel you want into the image.

Is this what you were looking for?

On Thu, Dec 29, 2016 at 3:57 PM Justin S <jsch...@gmail.com> wrote:

I'm not sure but this get threadjacked? The original post was asking if there is a how-to on loading new kernels. Since the second post this has been all about Magic Mouse scrolling support, or whatever. I've been lurking for a few weeks and he original question is the reason I joined this group in the first place. Is there a decent how-to of sorts? Thanks!

[Paco GB]

Yes @Justin S. the thread was hijacked! ;)

No @Prathmesh Prabhu  that was not what i was looking for.

What I'm trying to do is to load my own  modified kernel into ChromeOS, not building a ChromiumOS version with a modified kernel. 

The difference basically is that I would want to keep ChromeOS and the Play store.   

I made some progress though. I saw that the kernels (A,B and C) are stored in different partitions, and those partitions are selected based on the priority flag set by cgpt.

So following the information at the end of this page:

https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/custom-firmware

I signed the bzImage file of the kernel i did compile using the command:

echo blah > dummy.txt

vbutil_kernel --pack kernelpart.bin \

--keyblock /usr/share/vboot/devkeys/kernel.keyblock \

--signprivate /usr/share/vboot/devkeys/kernel_data_key.vbprivk \

--version 1 \

--vmlinuz ${MY_BINARY} \

--bootloader dummy.txt \

--config dummy.txt \

--arch x86

and then i tried to copy that signed kernel image to the non active kernel partition  ( I did choose the one without the "successful" flag equal to 1, because I imagined that is the non active partition)

  dd if=kernelpart.bin of=/dev/sda4

Finally i rebooted the system and... it did not work, the system tried to load the new kernel and i got a black screen, then i turned the computer off and on again and it fallback to the previous kernel.

Any help at this point? Have anyone tried something similar? I saw that "make_dev_ssd.sh"  moves the kernel to a temp folder, makes some modifications and load it back to it's partition, so maybe there is some insights  there on how to do it. I'll keep you updated.

[Ausmus, James]

Try: http://www.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-faq#TOC-How-to-quickly-test-kernel-modifications-the-fast-way-

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James Ausmus
ChromeOS Integration Architect
SSG-OTC ChromeOS Integration