问题
I am having problems getting any kernel modules to build on my machine. Whenever I build a module, modpost always says there are zero modules:
MODPOST 0 modules
To troubleshoot the problem, I wrote a test module (hello.c):
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
#include <linux/init.h> /* Needed for the macros */
static int __init hello_start(void)
{
printk(KERN_INFO "Loading hello module...\n");
printk(KERN_INFO "Hello world\n");
return 0;
}
static void __exit hello_end(void)
{
printk(KERN_INFO "Goodbye Mr.\n");
}
module_init(hello_start);
module_exit(hello_end);
Here is the Makefile for the module:
obj-m = hello.o
KVERSION = $(shell uname -r)
all:
make -C /lib/modules/$(KVERSION)/build M=$(shell pwd) modules
clean:
make -C /lib/modules/$(KVERSION)/build M=$(shell pwd) clean
When I build it on my machine, I get the following output:
make -C /lib/modules/2.6.32-27-generic/build M=/home/waffleman/tmp/mod-test modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-27-generic'
CC [M] /home/waffleman/tmp/mod-test/hello.o
Building modules, stage 2.
MODPOST 0 modules
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-27-generic'
When I make the module on another machine, it is successful:
make -C /lib/modules/2.6.24-27-generic/build M=/home/somedude/tmp/mod-test modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.24-27-generic'
CC [M] /home/somedude/tmp/mod-test/hello.o
Building modules, stage 2.
MODPOST 1 modules
CC /home/somedude/tmp/mod-test/hello.mod.o
LD [M] /home/somedude/tmp/mod-test/hello.ko
make[1]: Leaving directory `/usr/src/linux-headers-2.6.24-27-generic'
I looked for any relevant documentation about modpost, but found little. Anyone know how modpost decides what to build? Is there an environment that I am possibly missing?
BTW here is what I am running:
uname -a
Linux waffleman-desktop 2.6.32-27-generic #49-Ubuntu SMP Wed Dec 1 23:52:12 UTC 2010 i686 GNU/Linux
Edit
Here is make ran with V=1:
make -C /lib/modules/2.6.32-27-generic/build M=/home/waffleman/tmp/mod-test modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-27-generic'
test -e include/linux/autoconf.h -a -e include/config/auto.conf || ( \
echo; \
echo " ERROR: Kernel configuration is invalid."; \
echo " include/linux/autoconf.h or include/config/auto.conf are missing."; \
echo " Run 'make oldconfig && make prepare' on kernel src to fix it."; \
echo; \
/bin/false)
mkdir -p /home/waffleman/tmp/mod-test/.tmp_versions ; rm -f /home/waffleman/tmp/mod-test/.tmp_versions/*
make -f scripts/Makefile.build obj=/home/waffleman/tmp/mod-test
gcc -Wp,-MD,/home/waffleman/tmp/mod-test/.hello.o.d -nostdinc -isystem /usr/lib/gcc/i486-linux-gnu/4.4.3/include -Iinclude -I/usr/src/linux-headers-2.6.32-27-generic/arch/x86/include -include include/linux/autoconf.h -Iubuntu/include -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -fno-delete-null-pointer-checks -O2 -m32 -msoft-float -mregparm=3 -freg-struct-return -mpreferred-stack-boundary=2 -march=i586 -mtune=generic -maccumulate-outgoing-args -Wa,-mtune=generic32 -ffreestanding -fstack-protector -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -Wframe-larger-than=1024 -fno-omit-frame-pointer -fno-optimize-sibling-calls -pg -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fno-dwarf2-cfi-asm -fconserve-stack -DMODULE -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(hello)" -D"KBUILD_MODNAME=KBUILD_STR(hello)" -c -o /home/waffleman/tmp/mod-test/.tmp_hello.o /home/waffleman/tmp/mod-test/hello.c
set -e ; perl /usr/src/linux-headers-2.6.32-27-generic/scripts/recordmcount.pl "i386" "32" "objdump" "objcopy" "gcc" "ld" "nm" "" "" "1" "/home/waffleman/tmp/mod-test/hello.o";
(cat /dev/null; echo kernel//home/waffleman/tmp/mod-test/hello.ko;) > /home/waffleman/tmp/mod-test/modules.order
make -f /usr/src/linux-headers-2.6.32-27-generic/scripts/Makefile.modpost
scripts/mod/modpost -m -a -i /usr/src/linux-headers-2.6.32-27-generic/Module.symvers -I /home/waffleman/tmp/mod-test/Module.symvers -o /home/waffleman/tmp/mod-test/Module.symvers -S -w -s
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-27-generic'
waffleman@waffleman-desktop:~/tmp/mod-test$ cat /home/waffleman/tmp/mod-test/modules.order
kernel//home/waffleman/tmp/mod-test/hello.ko
回答1:
I spent all day glued to my computer fighting this precise problem..which ended up mysteriously disappearing like for OP.
I can at least offer this meager detail from my experience: I was getting the same output as OP (for make V=1) and putting print statements in ${kernel_directory}/scripts/makefile.build showed that obj-m was strangely NOT being set after including my makefile, even though it was clearly typed as above.
I did a bunch of fooling around with the line "obj-m += hello.o" and the ones around it. Eventually it magically worked..although it looked exactly the same as before in the end. Maybe I had copied those lines from a tutorial online and it contained some sort of invalid/incorrect character?
For anyone experiencing this, verify that obj-m is in fact getting set to hello.o
If it mysteriously isn't, delete the line, hell the whole Makefile, and retype it.
I know that's not much help; I wish I could reproduce what happened!
回答2:
In another thread I found that when I copy pasted the makefile contents, the -C after make was using the wrong "-" symbol and I had to re type it. It just so happens that this is the case for the obj-m += ... line above. You need to retype that character to make it valid. This should hopefully be found by anyone following the hello world module tutorial.
回答3:
I just ran into this same problem and for me it was caused by changing the default grep options via the GREP_OPTIONS environment variable. I didn't dig into the details, but something in the module build process didn't like my alternate grep output (include file name and line number). Removing the GREP_OPTIONS environment variable fixed things right up.
回答4:
This happens because when you copy the make file contents from the PDF or any other tutorial websites and use it as it is. While you do a copy-paste, the contents will appear a bit weird in Linux environment. ie; Some special character issues will be there. If you retype the contents in Linux environment and do a make, this should work.
回答5:
On the machine that fails does your .config have module support disabled?
Try doing "make menuconfig" and make sure module support is enabled.
回答6:
I can only guess your kernel build environment is botched, because it passes both the theoretical check (the look of the developer) as well as the practical test:
make -C /lib/modules/2.6.36-rc8-32-desktop/build M=/dev/shm modules
make[1]: Entering directory `/usr/src/linux-2.6.36-rc8-32-obj/x86_64/desktop'
make -C ../../../linux-2.6.36-rc8-32 O=/usr/src/linux-2.6.36-rc8-32-obj/x86_64/desktop/. modules
CC [M] /dev/shm/hello.o
Building modules, stage 2.
MODPOST 1 modules
CC /dev/shm/hello.mod.o
LD [M] /dev/shm/hello.ko
make[1]: Leaving directory `/usr/src/linux-2.6.36-rc8-32-obj/x86_64/desktop'
回答7:
The error mysteriously went away. If anyone has an idea what could cause this. I'd like to know in case there is a next time.
回答8:
I guess you copied the contents of the Makefile from a PDF or some HTML document. The hyphens used are somewhat weird. Just try replacing the hyphens in the makefile; it will work like a charm.
回答9:
Try to remove modules string from the Makefile:
obj-m = hello.o
KVERSION = $(shell uname -r)
all:
make -C /lib/modules/$(KVERSION)/build M=$(shell pwd) # <--
clean:
make -C /lib/modules/$(KVERSION)/build M=$(shell pwd) clean
回答10:
I was able to solve this problem by putting the
obj-m += <module name>.o
In a separate file named Kbuild. See Linux/documentation/kbuild/modules.txt for a hint as to why this might work
回答11:
I had the same problem. Finally, I rebuilt the kernel, rewrote the makefile. It worked finally.
I guess the main reason is because I had M=$(PWD) modules in the following line right after make ARCH=arm...
回答12:
I solved this problem by correcting Makefile, i.e.:
obj-m := modulename.o
来源：https://stackoverflow.com/questions/4715259/linux-modpost-does-not-build-anything