Hi,
For my pi I needed a button to safely shut it down. Found the gpio-shutdown overlay you can add in config.txt. This adds some stuff in the device tree. This little driver makes use of that.
Code is
here.
Should I just leave it there, or add it to ports somehow? I would like a code review, because it is my first kernel module, I only wrote some bare metal drivers for embedded stuff before.
I got a question for you - I am in the same boat you are in (lots of embedded experience - and decades device driver development - but currently experimenting with FreeBSD).
1) are you cross developing ? meaning is your development on an x86/x86-64 but you are building for an arm like i am ?
2) how did you get the Makefile to build for arm on the development host ?
I grabbed the skeleton.c example driver from the freebsd architecture handbook as well as the 9 line Makefile
SRCS=skeleton.c
KMOD=skeleton
.include <bsd.kmod.mk>
Now when I run
make TARGET=arm TARGET_ARCH=armv7
**It generates a module thats clearly built for x86-64 my host development machine and NOT for the target I specified**
machine -> /home/devel/nfsroot/usr/src/sys/amd64/include
x86 -> /home/devel/nfsroot/usr/src/sys/x86/include
i386 -> /home/devel/nfsroot/usr/src/sys/i386/include
Warning: Object directory not changed from original /home/devel/nfsroot/bsd_example_driver
cc -O2 -pipe -fno-strict-aliasing -Werror -D_KERNEL -DKLD_MODULE -nostdinc -DHAVE_KERNEL_OPTION_HEADERS -include /home/devel/nfsroot/obj/home/devel/nfsroot/usr/src/arm.armv7/sys/GENERIC/opt_global.h -I. -I/home/devel/nfsroot/usr/src/sys -I/home/devel/nfsroot/usr/src/sys/contrib/ck/include -fno-common -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -ffile-prefix-map=/home/devel/nfsroot/usr/src/sys=/usr/src/sys -ffile-prefix-map=/home/devel/nfsroot/obj/home/devel/nfsroot/usr/src/arm.armv7/sys/GENERIC=/usr/obj/usr/src/amd64.amd64/sys/GENERIC -ffile-prefix-map=/home/devel/nfsroot/bsd_example_driver=/usr/obj/usr/src/amd64.amd64/sys/GENERIC/modules/usr/src/sys/modules/bsd_example_driver -fdebug-prefix-map=./machine=/usr/src/sys/amd64/include -fdebug-prefix-map=./x86=/usr/src/sys/x86/include -fdebug-prefix-map=./i386=/usr/src/sys/i386/include -I/home/devel/nfsroot/obj/home/devel/nfsroot/usr/src/arm.armv7/sys/GENERIC -MD -MF.depend.skeleton.o -MTskeleton.o -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float -fno-asynchronous-unwind-tables -ffreestanding -fwrapv -fstack-protector -Wall -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wcast-qual -Wundef -Wno-pointer-sign -D__printf__=__freebsd_kprintf__ -Wmissing-include-dirs -fdiagnostics-show-option -Wno-unknown-pragmas -Wno-error=tautological-compare -Wno-error=empty-body -Wno-error=parentheses-equality -Wno-error=unused-function -Wno-error=pointer-sign -Wno-error=shift-negative-value -Wno-address-of-packed-member -Wno-format-zero-length -mno-aes -mno-avx -std=gnu99 -c skeleton.c -o skeleton.o
ld -m elf_x86_64_fbsd -warn-common --build-id=sha1 -T /home/devel/nfsroot/usr/src/sys/conf/ldscript.kmod.amd64 -r -o skeleton.ko skeleton.o
:> export_syms
awk -f /home/devel/nfsroot/usr/src/sys/conf/kmod_syms.awk skeleton.ko export_syms | xargs -J% objcopy % skeleton.ko
objcopy --strip-debug skeleton.ko
What am I doing wrong?
