Issue in installing integration branch kernel in 820c

Products Support DragonBoard 820c
#1

Hi,

I have build the kernel 4.14 from source and could install it in my 820c successfully. But unfortunately it was not able to detect the sd card. From the forum, I came to know that, this issue with the sd card is fixed with later kernel versions. So I am trying to build and install the integration branch by checking it out using the command
“git checkout integration-linux-qcomlt” .

I could build it successfully and could make ’ boot.img’.

I did “sudo fastboot flash boot boot.img”

After this I tried rebooting the board,but nothing is happening (Board is not coming up).

I could boot the board with the pre build images,
$sudo fastboot flash boot boot-linaro-buster-dragonboard-820c-221.img
$ sudo fastboot flash rootfs linaro-buster-alip-dragonboard-820c-221.img
But the kernel is 4.14.

Could you guys help me with why I am not able to boot with the newly built kernel?

#2

hi,

the integration branch is really for kernel developers and people who really love to ride on the edge! So based on your experience, and what you want to achieve, the integration branch won’t be much helpful. Most of the time it does not include all the features that we have in the release branch.

The integration branches changes every day, it’s not meant to be stable, it changes everytime linus’ master branch changes, or eveytime one of our dev makes a change… Right now , it’s based on bleeding edge 4.18-rc2, and we have a few issues…

The SD card issue you mention is known, especially with UHS SD CARDS (class 10), class 4 cards should work fine. So you can either use a lower speed card for now, or if you want a little bit of adventure, here is a branch of the “fix” for UFS cards that can be merged in the 4.14 release branch.

https://git.linaro.org/people/georgi.djakov/linux.git/log/?h=bus-scaling-4.14

It is not well tested yet, and might have rough edges, but it’s much less on the edge than the integration branch. I am planning to look at this branch and test next week… but if you come up with anything on your end first, please share!

#3

Thanks a lot. I will share the results.

But I wonder why my board is not even getting booted. I am suspecting that I am not doing it properly.

I am new to this kernel build scenario.

Could you please tell me the difference between
export cmdline=“root=/dev/ram0 rw rootwait console=ttyMSM0,115200n8” and
export cmdline=“root=/dev/disk/by-partlabel/rootfs rw rootwait console=ttyMSM0,115200n8”
which is supplied as argument to mkbootimg tool.

In

they do
both
sudo fastboot flash boot boot-linaro-buster-dragonboard-820c-BUILD.img
sudo fastboot flash rootfs linaro-buster-alip-dragonboard-820c-BUILD.img

In my case , the instructions are not asking me to do “sudo fastboot flash rootfs”
Why it is so? What is the difference between the both.

#4

the ‘root’ argument on the kernel command line is used by the kernel to mount the initial file system, at the end of the kernel boot (when it gets from kernel to user space).

/dev/ram0 means that you are mounting an init ramdisk, while /dev/disk/by-partlabel/rootfs means you will be trying to mount the partition called ‘rootfs’ as a the root FS.

your board might not boot because the integration branch might be broken. it can happen. it’s not a stable branch, breakage are not unexpected on that branch.

#5

Thanks a lot for the informative reply.