CODEWITHSUNDEEP
androidlinux-kernel
Eduardo Mirola
Eduardo Mirola

Reputation: 61

Cross compile LKM module for Android platform

For work reasons, I need to develop a LKM for Android platform. I'm not very sure how to cross compile my AndroidModule.c and what tools to use for that. I guess that I'll need the source code of Android in order to tell the compiler to link the libraries from there right? I will also need to download the ARM compiler for Android. I think with those three things is enough (LKM Code in C, Android Source Code, ARM compiler for android). The problem is that I can't find any tutorial that explains how to compile LKM for Android. I'll be very pleased to have more info about it.

Upvotes: 2

Views: 4381

Answers (3)

ajpyles
ajpyles

Reputation: 628

Here's a makefile that I use to build modules for Android. I'm assuming you have a copy of the linux source somewhere and that you have built the kernel for your phone. In your module directory I put a Makefile like this:

ifneq ($(KERNELRELEASE),)
    obj-m := mymod.o
else
    COMPILER ?=/pathtoandroid/prebuilt/linux-x86/toolchain/arm-eabi-4.4.0/bin/arm-eabi-
    CROSS_COMPILE ?=$(COMPILER)
    ARCH ?=arm
    KERNELDIR ?= /home/kernel/androidkerneldir/
    PWD := $(shell pwd)
    EXTRACFLAGS += -I$(PWD)/somedirectory/shomewhere
default:
    $(MAKE) -C $(KERNEL_DIR) M=`pwd` ARCH=$(ARCH) CROSS_COMPILE=$(COMPILER) EXTRA_CFLAGS=$(EXTRACFLAGS) modules
clean:
    rm *.o *.ko
install:
    adb push mymod.ko /system/lib/modules

This should do it for you. Make sure you have write permissions to /system directory.

Upvotes: 1

Andy
Andy

Reputation: 255

This should help.

To cross compile a module you'll need the kernel source code and the ARM compiler which is in the Android tool chain. You'll need a Makefile something along the lines of

obj-m:= AndroidModule.o

all: module

module:
    $(MAKE) -C $(KERNELSRC) SUBDIRS=$(PWD) modules
clean:
    $(MAKE) -C $(KERNELSRC) SUBDIRS=$(PWD) clean
    @rm -f Module.symvers Module.markers modules.order

Then compile by configuring CROSS_COMPILE as the ARM compiler and KERNELSRC as the kernel source location, and calling make. Here's the command I use on 0xdriod.

CROSS_COMPILE=~/beagle-eclair/prebuilt/linux-x86/toolchain/arm-eabi-4.4.0/bin/arm-eabi- ARCH=arm KERNELSRC=~/kernel make

Upvotes: 0

TheCottonSilk
TheCottonSilk

Reputation: 8812

Try the Android URL at the bottom it has detailed instructions on how to build the source.

Then follow this URL for final building (this is for dream release), I am assuming the procedure should hold good for other releases as well.

Upvotes: 0

Related Questions