out-of-tree | out-of-tree kernel { module , exploit } development tool | Hacking library

I think I solved the issue (also thanks to 0andriy's comment):

My mistake was that I treated the IPI register space

Inspecting dmesg on first insmod it was saying that the module was already loaded. As I had never loaded this before, this prompted me to think that this name was already taken. Low and behold, renaming module.c/module.o --> example.c/example.o fixed the problem. The invalid parameters message was what threw me.

There are a couple of options. For example: Format the item yourself with a new command. Then you can decide the spacing yourself.

1. Where should the driver exactly placed? I tried /lib/modules/5.4.79-v7, /lib/modules/5.4.79-v7/build

Answer: The driver is placed under /lib/modules/5.4.79-v7/extra if it is an extra module and build with.

The issue was because of a mounted disk which I had deleted and, upon doing so, learned that I setup the fstab wrong for that disk. This made the OS unbootable.

Solution was to delete the instance (but not the boot disk), create a temporary instance with the boot disk attached, fix the fstab, delete temporary instance, then create a new instance again but with the now-fixed disk as the boot disk.

There are only two riscv triple defined in llvm/include/llvm/ADT/Triple.h: riscv32 and riscv64.

By default HasStdExtV which is the flag corresponding to experimental-v in initialized to false in llvm/lib/Target/RISCV/RISCVSubtarget.h, if you want to use this extension you need to enable this feature.

Clangs seems also supporting this feature. In clang/lib/Driver/ToolChains/Arch/RISCV.cpp you can see that march support v feature and generate experimental-v for llc.

There is nothing in include/llvm/IR/IntrinsicsRISCV.td about Vector extension , however you can find the description of the instructions from the standard 'V' Vector extension in llvm/lib/Target/RISCV/RISCVInstrInfoV.td. It still experimental. In clang also you can find that even if the v extension is supported, in the default you can see // Currently LLVM supports only "mafdc". in clang/lib/Driver/ToolChains/Arch/RISCV.cpp

There are several ways to achieve what you want (taking into account different aspects, like module can be compiled in or be a module).

1. Convert Out-Of-Tree module to be In-Tree one (in your custom kernel build). This will require simple export and import as you basically done and nothing special is required, just maybe providing a header with the symbol and depmod -a run after module installation. Note, you have to use modprobe in-tree which reads and satisfies dependencies.
2. Turn other way around, i.e. export symbol from in-tree module and file it in the out-of-tree. In this case you simply have to check if it has been filed or not (since it's a MAC address the check against all 0's will work, no additional flags needed)

BUT, these ways are simply wrong. The driver and even your patch clearly show that it supports OF (Device Tree) and your board has support of it. So, this is a first part of the solution, you may provide correct MAC to the network card using Device Tree.

In the case you want to change it runtime the procfs approach is very strange to begin with. Network device interface in Linux has all means to update MAC from user space at any time user wants to do it. Just use ip command, like /sbin/ip link set <$ETH> addr <$MACADDR>, where <$ETH> is a network interface, for example, eth0 and <$MACADDR> is a desired address to set.

So, if this question rather about module symbols, you need to find better example for it because it's really depends to use case. You may consider to read How to export symbol from Linux kernel module in this case? as an alternative way to exporting. Another possibility how to do it right is to use software nodes (it's a new concept in recent Linux kernel).

Found the solution: I had to add dts_fixup.h to the bottom of my soc folder.

Changes:

CMakeLists.txt