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I am new in kernel programming.
For implementing my project work, I have downloaded the latest stable kernel (v4.3) from kernel.org.
Just for checking I have copied a few files from the kernel directories into my project directory. Made changes to it and inserted a few more code to it.
Then I compiled on SLES11 Linux kernel using
make -C /lib/modules/$(uname -r)/build M=$PWD modules
I have used the below makefile
obj-m := my_module.o
my_module-objs := module_main.0 other_module1.o other_module2.o other_module3.o
It compiled successfully. But when I tried to insert into the kernel using
insmod my_sample.ko
It showed the following
disagrees about version of symbol symbol_name
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insmod is similar to modprobe: it can insert a module into the Linux kernel. Unlike modprobe, however, insmod does not read its modules from a set location, automatically insert them, and manage any dependencies. insmod can insert a single module from any location, and does not consider dependencies when doing so.
Suppose, if I loaded a module, which has symbols defined in some other module (this module path is given inside the main module). So, modprobe loads the main module and the dependent module. But if insmod is used, it won't load the dependency, and hence it will give compilation errors like Unresolved symbols .
Insmod copies the module into the allocated space and relocates it so that it will run from the kernel address that it has been allocated. This must happen as the module cannot expect to be loaded at the same address twice let alone into the same address in two different Linux systems.
During a kernel build, a file named Module. symvers will be generated. Module. symvers contains all exported symbols from the kernel and compiled modules. For each symbol, the corresponding CRC value is also stored.
You need to build your kernel module against the same version kernel you are going to run. Thus if you have kernel 4.3 sources that you have downloaded you need to compile that version of the kernel and boot with that running before trying to load your kernel.
You have two solutions then:
zypper install kernel-source on SLES or an equivalent command on other distributions.)
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The problem here is that your Kernel module is using the exported symbols of other kernel modules which in this case appears to be the linux InfiniBand RDMA stack's exported methods or symbols.
To solve the symbol version problems, copy the Module.symvers file from the
/usr/src/ofa-kernel
directory and paste it to your current working directory. Then you make your modules again. Now the insmod should work perfectly fine.
NOTE: The Module.symvers file contains information of all the kernel module exported symbol. So by copying it to your working directory, you are helping kbuild to know more about the used exported symbols.
And if you don't find Module.symvers or it is empty, then create one using create_Module.symvers.sh
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