MarkoPapic/mpfs

Trying out

Install the kernel module:

sudo insmod mpfs.ko

Check the registered file systems:

cat /proc/filesystems | grep mpfs

Check the logs:

sudo dmesg | tail -4

Create an empty file:

dd if=/dev/zero of=dev/fake_device bs=1024 count=104857600

Build the mkfs tool:

make mkfs_mpfs

Run mkfs:

./mkfs_mpfs dev/fake_device

Create a mpfs directory in ~/media

Mount the file system:

sudo mount -t mpfs -o loop dev/fake_device ~/media/mpfs

Troubleshooting

Module verification failed: signature and/or required key missing - tainting kernel

If you see the following line in your make build output, that is probably what is causing it:

Skipping BTF generation for /home/marko/code/mpfs/src/mpfs.ko due to unavailability of vmlinux

You can fix it by installing dwarves

apt-get install dwarves

check if vmlinux is now present

ls /sys/kernel/btf

and copy it to where it is expected to be found

cp /sys/kernel/btf/vmlinux /usr/lib/modules/$(uname -r)/build/

An alternative is to sign your modules manually.

pr_debug logs not visible in dmesg

Add CFLAGS_mpfs.o := -DDEBUG to your Kbuild file.

An alternative would be to use pr_warn instead.

VSCode intellisense reports a bunch of errors even though the build succeeds

It boils down to c_cpp_properties.json configuration. Probably one of the following:

• includePath
• defines
• browse->path
• compilerPath