Kernel compiling for Pi 2

by **Seabug** » Sat Feb 21, 2015 4:20 pm

Hi,

I am trying to compile the Raspbian kernel for my new Pi 2 ( I need support for ELO / Egalax Touch).
I can't find any hints how to configure the kernel sources / Makefile to generate me a kernel7.img
Anyone, who can help ?

Thanks, Steffen

by **n1ks** » Sat Feb 21, 2015 10:06 pm

Steffen,

Hi, when compiling for the RPI.v2 i used bcm2709_defconfig for the config instead of bcmrpi_defconfig. Other than that, the steps are the same as compiling for rpi.v1.
Once cross compile was complete i copied arch/arm/boot/Image (or zImage for a smaller kernel) to kernel7.img then copied it on to the sd card.

Hope that makes sense.

nik

by **Seabug** » Sun Feb 22, 2015 1:25 pm

Thanks, Nik.
I got the kernel compiled now (build on the Pi 2 with the power of 4 processor kernels

).
Steffen

by **wyattwong** » Sun Feb 22, 2015 3:01 pm

Seabug wrote:Thanks, Nik.
I got the kernel compiled now (build on the Pi 2 with the power of 4 processor kernels ).
Steffen

Can you provide the steps to compile the kernel and generate kernel.img and kernel7.img ? Maybe a simple tutorial ?

What's the difference between kernel.img and kernel7.img ?

by **Seabug** » Mon Feb 23, 2015 12:27 pm

Actually I followed the instruction in the manual.
Since I was new to kernel compiling too, I made the assumption that the compiling generates both images, which is wrong.
The difference is made by the .config file, which determins the architecture. However, the make generates a compressed image and a uncompressed image.
To generate a Pi2 Image, you can use bcm2709_defconfig instead of bcmrpi_defconfig to prepare your .config file.
After I used menuconfig to find and activate my modules.
It was quite time consuming, so I opened the .config with vi and just changed the entries for my elo and egalax touch.
The compiling worked fine. I had problems using the uncompressed kernel, but the zimage worked fine.
However, I still didn't get my touch-screens working, but this seems to bee a problem of the device aliases.
Still working on it.

Steffen

by **n1ks** » Tue Feb 24, 2015 12:40 pm

If you run rpi-update you should find egalax touchscreen module has now been added to the kernel. (Have tested on vanilla Raspbian install using rpi v.2)

Cross-compile is no longer required.

You will however still need to calibrate the screen using xinput_calibrator.

nik

by **eriktheitalian** » Tue Feb 24, 2015 12:47 pm

I'm curious about BFS cpu scheduler patch. Is it effective or not ?

by **Seabug** » Tue Feb 24, 2015 1:24 pm

n1ks wrote:If you run rpi-update you should find egalax touchscreen module has now been added to the kernel.
(Have tested on vanilla Raspbian install using rpi v.2)
Cross-compile is no longer required.
You will however still need to calibrate the screen using xinput_calibrator.

nik

Hi Nik,

I found some posts regarding the activated Egalax in the kernel config.
When I copied the sources, it was already activ in the config, but compiled kernels not yet available.
I am really looking forward to this. Anyway I still need ELO too, so I will have to compile my own kernel.
Compiling with make -j 6 is fast. I am to lazy to switch hard disks to Ubuntu in my PC and did not yet try to cross compile it under FreeBSD, even thought the ARM cross compiler is available under FreeBSD too. Maybe I will give it a try in the next days.
ELO/Penmount and Egal touch screens are quite cheap now and I see many Pi projects going on with it.
I actually plan to replace a ARM-Linux based PLC, which has touch support - but I don't need IO cards.
I will use remote IOs, so the Pi 2 is much more versatile, much faster and cheaper too.
I just could not yet find any help regarding the unrecognised Penmount touch.

Regards, Steffen

Update: I got it working :-)

All touchscreens included, ELO, Egalax, Penmount.
Have some issues with xinput_calibration, values are in wrong order, but once you know, you can correct manually.
BTW: Compiling the kernel in exactly 2.5h :-)

by **andrea.cane** » Tue Aug 25, 2015 6:10 pm

Hello

is very interesting I'm in the same situation, I have a LCD touchscrenn and would like to compile a kernel with all drivers for supported touch because I do not know what is the mine, but I can not find a guide that will explain step by step clear :evil:

how to fill the new kernel, you may share it with me and also with the group the steps or help you followed to be able to compile without error.

thanks in advance and good work :roll:

by **Seabug** » Wed Aug 26, 2015 8:24 am

Hi Andrea,

please take a look at my post from February 23rd. I used vi (or any other editor) to modify the .config file, rather than using the script. Currently I am in my Vietnam office and I have not touchscreen here, but in around 10 days I will return to Germany and compile a new kernel. I can send you the result or also the .config file for further modifications.

regards, Steffen