Few questions about kernel & kernel module in ChromeOS

Lak Fu

unread,

Mar 1, 2018, 10:22:13 PM3/1/18

to Chromium OS dev

Hi, everyone.

I follow the guide http://www.chromium.org/chromium-os/developer-guide to build a ChromeOS image successfully.

But I have few questions,

1. Which kernel (version) will be built in the image? I saw the source code contains few different kernel (version).

2. If I want to add a kernel module, is there have a quick way to re-gen the image?

I have checked another guide http://www.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-configuration, but I am not sure how to make a complete ChromeOS image.

Thank everyone.

Mike Frysinger

unread,

Mar 2, 2018, 12:41:00 AM3/2/18

to Lak Fu, Chromium OS dev

the kernel version used depends on the board you built. if you look at the build_packages or build_image output, look for the sys-kernel/xxx packages to find out.

-mike

--
--
Chromium OS Developers mailing list: chromiu...@chromium.org
View archives, change email options, or unsubscribe:
http://groups.google.com/a/chromium.org/group/chromium-os-dev?hl=en

ggg

unread,

Mar 2, 2018, 12:11:36 PM3/2/18

to Chromium OS dev

What Mike said is correct. Just adding a few more tips.

On Thursday, March 1, 2018 at 7:22:13 PM UTC-8, Lak Fu wrote:

Hi, everyone.
I follow the guide http://www.chromium.org/chromium-os/developer-guide to build a ChromeOS image successfully.
But I have few questions,
1. Which kernel (version) will be built in the image? I saw the source code contains few different kernel (version).

First build the image for the boards you have available and can test on. Then look in /build/$BOARD/boot for the kernel version.

2. If I want to add a kernel module, is there have a quick way to re-gen the image?

For development, you can use "build_image ... --noenable_rootfs_verification". Then once your image is installed on the test device, "mount -o remount,rw /" and you can add/remove modules that match the kernel you built. Take a look at ~/trunk/src/scripts/update_kernel.sh and see if that will work for you.

I have checked another guide http://www.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-configuration, but I am not sure how to make a complete ChromeOS image.

The developer guide you referenced tells you how to build a complete Chrome OS image.

It's really just a few steps (that can each take a while):

1) create the local repo with repo init and repo sync

2) enter the chroot and "./setup_board --board=$BOARD"

3) build_packages --board=$BOARD

4) build_image test --board=$BOARD ...

5) cros flash $IP (or usb:// to install the test image the first time)

If you have questions about any of the steps, first read the developer guide instructions and quote the relevant section when you post your question.

cheers,

grant

Thank everyone.

kr...@flintos.io

unread,

Mar 4, 2018, 6:41:37 AM3/4/18

to Chromium OS dev

The kernel version to built is controlled by the kernel-XX use flag. It is defined in the profile/base/make.defaults file in board overlay. XX is something like 3_18, 4_4 etc. and it obviously means a kernel release version.

This use flag is used by the virtual/linux-sources ebuild. Depends on the exact kernel-XX use flag defined, this ebuild pulls in corresponding chromeos-kernel-XX package as its dependency, so that specific version of kernel package get build and installed when your run the build_package and build_image scripts.

Lak Fu

unread,

Mar 4, 2018, 11:40:39 PM3/4/18

to Chromium OS dev

Thank everyone, you give me a lot useful information.

Now, I am trying to build my own kernel but I found 2 ways to build it.

1. FEATURES="noclean" cros_workon_make --board=${BOARD} --install chromeos-kernel-4_4

from http://www.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-faq

2. just 'make' and 'make uImage' in kernel source folder

from http://www.chromium.org/chromium-os/how-tos-and-troubleshooting/kernel-configuration

Method 2 is succeed but method 1 failed, my question is, if I built the uimage with 'make uImage', can I update the kernel with the below script?

~/trunk/src/scripts/update_kernel.sh --remote <ip of target>

The error message is the following, actually it really confuse me ...

If you like to give me some help, i will very thank you.

(cr) ((3730ff1728c1...)) lake@OA-106028 ~/trunk/src/third_party/kernel/v4.4 $ FEATURES="noclean" cros_workon_make --board=${BOARD} --install chromeos-kernel-4_4

>>> Emerging (1 of 1) sys-kernel/chromeos-kernel-4_4-9999::chromiumos for /build/amd64-generic/
* chromeos-kernel-4_4-R66-10315.0-1516619937.gcov.xz SHA256 SHA512 WHIRLPOOL size ;-) ... [ ok ]
* Running stacked hooks for pre_pkg_setup
* sysroot_build_bin_dir ... [ ok ]
* Determining the location of the kernel source code
* Found kernel source directory:
* /mnt/host/source/src/third_party/kernel/v4.4
* Found kernel object directory:
* /build/amd64-generic/usr/src/linux
* Found sources for kernel version:
* 4.4.112
* Running stacked hooks for post_pkg_setup
* python_eclass_hack ... [ ok ]
* Running stacked hooks for pre_src_unpack
* python_multilib_setup ... [ ok ]
>>> Unpacking source...
* Using local source dir(s): /mnt/host/source/src/third_party/kernel/v4.4
* path: /mnt/host/source/src/third_party/kernel/v4.4
* destdir: /build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999
* Using experimental inplace build in /mnt/host/source/src/third_party/kernel/v4.4.
* For inplace build you need to modify the sandbox
* Set SANDBOX_WRITE=/mnt/host/source in your env.
>>> Unpacking chromeos-kernel-4_4-R66-10315.0-1516619937.gcov.xz to /build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work
>>> Source unpacked in /build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work
* Running stacked hooks for post_src_unpack
* asan_init ... [ ok ]
>>> Preparing source in /build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999 ...
>>> Source prepared.
>>> Configuring source in /build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999 ...
* Using kernel config: chromiumos-x86_64
* - disabling framebuffer console config
* - enabling Support running virtual machines with KVM config
* - enabling CDC MBIM driver config
* - enabling TPM support config
* - enabling Transparent Hugepage Support config
* - enabling 802.1Q VLAN config
* - disabling VT console config
ERROR: ld.so: object 'libsandbox.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.
make -j8 O=/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4 LD=/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0/ld 'CC=x86_64-cros-linux-gnu-gcc -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' 'CXX=x86_64-cros-linux-gnu-g++ -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' HOSTCC=x86_64-pc-linux-gnu-gcc HOSTCXX=x86_64-pc-linux-gnu-g++ oldnoconfig
make[1]: Entering directory '/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4'
GEN ./Makefile
scripts/kconfig/conf --olddefconfig Kconfig
.config:4463:warning: override: reassigning to symbol FRAMEBUFFER_CONSOLE
.config:4472:warning: override: reassigning to symbol KVM
.config:4479:warning: override: reassigning to symbol VSOCKETS
.config:4481:warning: override: reassigning to symbol VIRTUALIZATION
.config:4485:warning: override: reassigning to symbol USB_NET_CDC_MBIM
.config:4488:warning: override: reassigning to symbol TCG_TPM
.config:4489:warning: override: reassigning to symbol TCG_TIS
.config:4493:warning: override: reassigning to symbol TRANSPARENT_HUGEPAGE
.config:4497:warning: override: reassigning to symbol VLAN_8021Q
.config:4500:warning: override: reassigning to symbol VT
.config:4501:warning: override: reassigning to symbol VT_CONSOLE
#
# configuration written to .config
#
make[1]: Leaving directory '/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4'
>>> Source configured.
>>> Compiling source in /build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999 ...
ERROR: ld.so: object 'libsandbox.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.
make -j8 O=/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4 LD=/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0/ld 'CC=x86_64-cros-linux-gnu-gcc -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' 'CXX=x86_64-cros-linux-gnu-g++ -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' HOSTCC=x86_64-pc-linux-gnu-gcc HOSTCXX=x86_64-pc-linux-gnu-g++ -k
make[1]: Entering directory '/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4'
CHK include/config/kernel.release
GEN ./Makefile
CHK include/generated/uapi/linux/version.h
CHK include/generated/utsrelease.h
CHK scripts/mod/devicetable-offsets.h
Using /mnt/host/source/src/third_party/kernel/v4.4 as source for kernel
/mnt/host/source/src/third_party/kernel/v4.4 is not clean, please run 'make mrproper'
in the '/mnt/host/source/src/third_party/kernel/v4.4' directory.
make[1]: *** [/mnt/host/source/src/third_party/kernel/v4.4/Makefile:1013: prepare3] Error 1
make[1]: Target '_all' not remade because of errors.
make[1]: Leaving directory '/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4'
make: *** [Makefile:150: sub-make] Error 2
make: Target '_all' not remade because of errors.
* __helpers_die: WARNING: emake failed
* If this failure is due to build-dir corruption, run:
* sudo rm -rf '/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4'
* ERROR: sys-kernel/chromeos-kernel-4_4-9999::chromiumos failed (compile phase):
* command: emake O=/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4 LD=/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0/ld CC=x86_64-cros-linux-gnu-gcc -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0 CXX=x86_64-cros-linux-gnu-g++ -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0 HOSTCC=x86_64-pc-linux-gnu-gcc HOSTCXX=x86_64-pc-linux-gnu-g++ -k
*
* Call stack:
* ebuild.sh, line 93: Called src_compile
* environment, line 5268: Called cros-kernel2_src_compile
* environment, line 1607: Called kmake '-k'
* environment, line 4200: Called cw_emake 'O=/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4' 'LD=/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0/ld' 'CC=x86_64-cros-linux-gnu-gcc -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' 'CXX=x86_64-cros-linux-gnu-g++ -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' 'HOSTCC=x86_64-pc-linux-gnu-gcc' 'HOSTCXX=x86_64-pc-linux-gnu-g++' '-k'
* environment, line 2257: Called die
* The specific snippet of code:
* die "command: emake $*";
*
* If you need support, post the output of `emerge --info '=sys-kernel/chromeos-kernel-4_4-9999::chromiumos'`,
* the complete build log and the output of `emerge -pqv '=sys-kernel/chromeos-kernel-4_4-9999::chromiumos'`.
* The complete build log is located at '/build/amd64-generic/tmp/portage/logs/sys-kernel:chromeos-kernel-4_4-9999:20180305-043835.log'.
* For convenience, a symlink to the build log is located at '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/temp/build.log'.
* The ebuild environment file is located at '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/temp/environment'.
* Working directory: '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999'
* S: '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999'

>>> Failed to emerge sys-kernel/chromeos-kernel-4_4-9999 for /build/amd64-generic/, Log file:

>>> '/build/amd64-generic/tmp/portage/logs/sys-kernel:chromeos-kernel-4_4-9999:20180305-043835.log'

* Messages for package sys-kernel/chromeos-kernel-4_4-9999 merged to /build/amd64-generic/:

* For inplace build you need to modify the sandbox
* Set SANDBOX_WRITE=/mnt/host/source in your env.
* Using kernel config: chromiumos-x86_64
* - disabling framebuffer console config
* - enabling Support running virtual machines with KVM config
* - enabling CDC MBIM driver config
* - enabling TPM support config
* - enabling Transparent Hugepage Support config
* - enabling 802.1Q VLAN config
* - disabling VT console config
* If this failure is due to build-dir corruption, run:
* sudo rm -rf '/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4'
* ERROR: sys-kernel/chromeos-kernel-4_4-9999::chromiumos failed (compile phase):
* command: emake O=/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4 LD=/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0/ld CC=x86_64-cros-linux-gnu-gcc -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0 CXX=x86_64-cros-linux-gnu-g++ -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0 HOSTCC=x86_64-pc-linux-gnu-gcc HOSTCXX=x86_64-pc-linux-gnu-g++ -k
*
* Call stack:
* ebuild.sh, line 93: Called src_compile
* environment, line 5268: Called cros-kernel2_src_compile
* environment, line 1607: Called kmake '-k'
* environment, line 4200: Called cw_emake 'O=/build/amd64-generic/var/cache/portage/sys-kernel/chromeos-kernel-4_4' 'LD=/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0/ld' 'CC=x86_64-cros-linux-gnu-gcc -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' 'CXX=x86_64-cros-linux-gnu-g++ -B/usr/x86_64-pc-linux-gnu/x86_64-cros-linux-gnu/binutils-bin/2.27.0' 'HOSTCC=x86_64-pc-linux-gnu-gcc' 'HOSTCXX=x86_64-pc-linux-gnu-g++' '-k'
* environment, line 2257: Called die
* The specific snippet of code:
* die "command: emake $*";
*
* If you need support, post the output of `emerge --info '=sys-kernel/chromeos-kernel-4_4-9999::chromiumos'`,
* the complete build log and the output of `emerge -pqv '=sys-kernel/chromeos-kernel-4_4-9999::chromiumos'`.
* The complete build log is located at '/build/amd64-generic/tmp/portage/logs/sys-kernel:chromeos-kernel-4_4-9999:20180305-043835.log'.
* For convenience, a symlink to the build log is located at '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/temp/build.log'.
* The ebuild environment file is located at '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/temp/environment'.
* Working directory: '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999'
* S: '/build/amd64-generic/tmp/portage/sys-kernel/chromeos-kernel-4_4-9999/work/chromeos-kernel-4_4-9999'

ggg於 2018年3月3日星期六 UTC+8上午1時11分36秒寫道：

ya...@flintos.io

unread,

Mar 5, 2018, 12:40:15 AM3/5/18

to Chromium OS dev

It looks like you have running 'cros_workon start' command with "chromeos-kernel-4_4", and building the kernel by 'make'. The solution:

1.You can clean the kernel directory by "/mnt/host/source/src/third_party/kernel/v4.4/make mrproper ".

2.Or running "cros_workon --board=amd64-generic stop chromeos-kernel-4_4" to change the source to remote repo.

If you want to build a package from the local source:

1. making some change to the local source code.

2. Build the package by "emerge-$BOARD $the-package-name". Example: "emerge-amd64-generic chromeos-kernel-4_4"

3. Deploy the new package to your client by "cros deploy $your-client-device-ip $the-package-name". Example: "cros deploy 192.168.10.2 chromeos-kernel-4_4". BTW, the command can't apply the new kernel to your client directly. You have to copy the kernel from root-partition to efi-partition manually.

Lak Fu

unread,

Mar 5, 2018, 3:23:21 AM3/5/18

to Chromium OS dev

yes, I fixed this problem. XD I forget use below command

chromeos/scripts/kernelconfig olddefconfig

But now I encounter new problem.... I cannot load my module on boot time.....

I almost try every ways.......

ya...@flintos.io於 2018年3月5日星期一 UTC+8下午1時40分15秒寫道：

Lak Fu

unread,

Mar 8, 2018, 10:57:15 PM3/8/18

to Chromium OS dev

Hi, everyone.

First, thank you guys give me so much information and answer my questions.

Now, I can build specific kernel and flash it to remote with script, and I can also rebuilt the image that include my new kernel.

But I encounter another problem, my developing kernel is ver 4.4, but I like to build a new image with 4.14.

How do I specific my target kernel to let build_package & build_image script reference use it?

Is it just need below command?

FEATURES="noclean" cros_workon_make --board=${BOARD} --install chromeos-kernel-4_14

Lak Fu於 2018年3月2日星期五 UTC+8上午11時22分13秒寫道：

Lak Fu

unread,

Mar 12, 2018, 9:40:02 PM3/12/18

to Chromium OS dev

Unfortunately, I am failed.

I following the guide that build a ChromeOS image with kernel 4.4.

Next I try to replace the kernel with 4.14 and I got some error message as below.

My command is:

cros_workon_make --board amd64-generic chromeos-kernel-4_14 --install

Error message in the following, is any suggestion here?

>>> Installing (1 of 1) sys-kernel/chromeos-kernel-4_14-9999::chromiumos to /build/amd64-generic/

* Removing /usr/lib*/*.la

* Removing /etc/init.d

* Removing /etc/conf.d

* Removing /etc/logrotate.d

* Removing /etc/sandbox.d

* Removing /usr/share/bash-completion

* Removing /usr/share/man

* Removing /usr/share/info

* Removing /usr/share/doc

* This package will overwrite one or more files that may belong to other

* packages (see list below). You can use a command such as `portageq

* owners / <filename>` to identify the installed package that owns a

* file. If portageq reports that only one package owns a file then do

* NOT file a bug report. A bug report is only useful if it identifies at

* least two or more packages that are known to install the same file(s).

* If a collision occurs and you can not explain where the file came from

* then you should simply ignore the collision since there is not enough

* information to determine if a real problem exists. Please do NOT file

* a bug report at http://bugs.gentoo.org unless you report exactly which

* two packages install the same file(s). See

* http://wiki.gentoo.org/wiki/Knowledge_Base:Blockers for tips on how to

* solve the problem. And once again, please do NOT file a bug report

* unless you have completely understood the above message.

*

* Detected file collision(s):

*

* /build/amd64-generic/usr/lib/debug/boot/vmlinux

* /build/amd64-generic/boot/vmlinuz

*

* Searching all installed packages for file collisions...

*

* Press Ctrl-C to Stop

*

* sys-kernel/chromeos-kernel-4_4-9999:0::chromiumos

* /build/amd64-generic/boot/vmlinuz

* /build/amd64-generic/usr/lib/debug/boot/vmlinux

*

* Package 'sys-kernel/chromeos-kernel-4_14-9999' NOT merged due to file

* collisions. If necessary, refer to your elog messages for the whole

* content of the above message.

>>> Failed to install sys-kernel/chromeos-kernel-4_14-9999 to /build/amd64-generic/, Log file:

>>> '/build/amd64-generic/tmp/portage/logs/sys-kernel:chromeos-kernel-4_14-9999:20180313-011344.log'

* Messages for package sys-kernel/chromeos-kernel-4_14-9999 merged to /build/amd64-generic/:

* For inplace build you need to modify the sandbox

* Set SANDBOX_WRITE=/mnt/host/source in your env.

* Using kernel config: chromiumos-x86_64

* - disabling framebuffer console config

* - enabling Support running virtual machines with KVM config

* - enabling CDC MBIM driver config

* - enabling TPM support config

* - enabling Transparent Hugepage Support config

* - enabling 802.1Q VLAN config

* - disabling VT console config