Hello there,
I am using Buildroot to compile the kernel for my ARM target, which is a Beaglebone black. This part works. Now I would like to use the crosscompiler available from the output of the buildroot in order to compile a "Hello World" Kernel module. I have already checked a regular c file Hello World and it crosscompiles on host and runs on the target correctly. I am having problems with setting up the whole environment for the kernel module development. There are many tutorials available for kernel modules development, but they assume developing on the target/ host. I am able to compile a native host x86 kernel module, that works.
I am still missing some dependencies when trying to crosscompile for the Beagle, I am not sure either I need to build some further packages, but when doing xconfig I think I checked everything related to the kernel modules. At the moment I have the following Makefile:
Code:
obj-m := simp.o
KERNELDIR ?= /home/lukasz/brl/Machine/beaglebone/build/linux-headers-a75d8e93056181d512f6c818e8627bd4554aaf92
PWD := $(shell pwd)
all: default
default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
And the example module code (simp.c):
Code:
#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");
static int hello_init(void)
{
printk(KERN_ALERT "Hello, world\n");
return 0;
}
static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, cruel world\n");
}
module_init(hello_init);
module_exit(hello_exit);
When trying to make:
Code:
make ARCH=arm CROSS_COMPILE=arm-buildroot-linux-uclibcgnueabihf- -I/home/lukasz/brl/Machine/beaglebone/build/linux-a75d8e93056181d512f6c818e8627bd4554aaf92/include -I/home/lukasz/brl/Machine/beaglebone/build/linux-a75d8e93056181d512f6c818e8627bd4554aaf92 -I/home/lukasz/brl/Machine/beaglebone/build/linux-a75d8e93056181d512f6c818e8627bd4554aaf92/include/generated/autoconf.h
I get the following error:
Code:
make -C /home/lukasz/brl/Machine/beaglebone/build/linux-headers-a75d8e93056181d512f6c818e8627bd4554aaf92 M=/tmp/test modules
make[1]: Entering directory '/home/lukasz/brl/Machine/beaglebone/build/linux-headers-a75d8e93056181d512f6c818e8627bd4554aaf92'
WARNING: Symbol version dump ./Module.symvers
is missing; modules will have no dependencies and modversions.
CC [M] /tmp/test/simp.o
In file included from <command-line>:0:0:
././include/linux/kconfig.h:4:32: fatal error: generated/autoconf.h: No such file or directory
#include <generated/autoconf.h>
^
compilation terminated.
scripts/Makefile.build:299: recipe for target '/tmp/test/simp.o' failed
make[2]: *** [/tmp/test/simp.o] Error 1
Makefile:1493: recipe for target '_module_/tmp/test' failed
make[1]: *** [_module_/tmp/test] Error 2
make[1]: Leaving directory '/home/lukasz/brl/Machine/beaglebone/build/linux-headers-a75d8e93056181d512f6c818e8627bd4554aaf92'
Makefile:8: recipe for target 'default' failed
make: *** [default] Error 2
Which I dont understand, since included the .h file specifically. I would appreciate all help regarding this. I was trying to find anyone else doing something similar (trying to cross compile a kernel module on the host using buildroot build tools), but was unable to. Most of the cases are already to advanced or dont apply to my problem.
