Compile kernel module for Pocketbook 740

[Entwickler]

I am trying to compile a kernel module for my Pocketbook 740 (Inkpad 3 Pro).
The device announces following kernel

Linux version 3.10.65+ (jenkins@bsp-builder) (gcc version 4.9.2 20140904 (prerelease) (crosstool-NG linaro-1.13.1-4.9-2014.09 - Linaro GCC 4.9-2014.09) ) #2 SMP

I have tried two kernel sources:

• get kernel from https://github.com/pocketbook/kernel-b288.git
• get vanilla kernel 3.10.65

I compiled them with

• gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf
• gcc-linaro-arm-linux-gnueabihf-4.9-2014.09_linux

using following commands:

#!/bin/sh
export KCFLAGS="-mcpu=cortex-a8 -march=armv7-a -mfpu=neon -mfloat-abi=softfp"
CROSS_PREFIX=/workspace/gcc-linaro-arm-linux-gnueabihf-4.9-2014.09_linux/bin/arm-linux-gnueabihf-
NCPUS=8
make ARCH=arm CROSS_COMPILE="${CROSS_PREFIX}" -j ${NCPUS} $1

Right now I am trying to insert the block device module loop.ko just to see if my build works. I seem to always get

$ insmod /mnt/ext1/loop.ko
insmod: can't insert '/mnt/ext1/loop.ko': invalid module format

When I consult file my module and the modules on the device look the same:

drivers/block/loop.ko: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), BuildID[sha1]=487b84d6a004392e0fe384329cb7ea2ffb87d38c, not stripped

epdc.ko: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), BuildID[sha1]=8c110ead8aa1506eee362cee022ba27f81394d0e, not stripped

Any help greatly appreciated.

[wold]

Out of curiosity, where/how do you run insmod? Rooted SSH, or using chroot?

[Entwickler]

Originally Posted by wold

Out of curiosity, where/how do you run insmod? Rooted SSH, or using chroot?

Yes, rooted the device and sshed to root.

[rantanplan]

Out of curiosity: Newer kerrnels won't work on the device?

[Entwickler]

Originally Posted by rantanplan

Out of curiosity: Newer kerrnels won't work on the device?

As far as I know you can not simply replace the kernel. The module for the eInk panel is closed source. So no point in trying that.

[wold]

Can dmsg provide more info?

Would this help? (if CROSS_COMPILE does not equal -C)
https://unix.stackexchange.com/quest...e-format-error

[Entwickler]

Originally Posted by wold

Can dmsg provide more info?

Would this help? (if CROSS_COMPILE does not equal -C)
https://unix.stackexchange.com/quest...e-format-error

Unfortunately dmsg is empty. I guess this is because of old and stripped down version of insmod? Will have a look at your link, thx.

[wold]

Originally Posted by Entwickler

Unfortunately dmsg is empty. I guess this is because of old and stripped down version of insmod?

Possibly. Or --level requires adjustment (consult dmesg --help + man pages). Or the buffer was cleared.

Else try:
echo Some message > /dev/kmsg
and check with dmesg. Assuming kmsg is available.

[Entwickler]

Originally Posted by wold

Possibly. Or --level requires adjustment (consult dmesg --help + man pages). Or the buffer was cleared.

Else try:
echo Some message > /dev/kmsg
and check with dmesg. Assuming kmsg is available.

I did everything from scratch and followed your advice and got some error output after all. Now the module is working. thx a million