FSKit: Implement a file system that runs in user space

macOS/iOS/iPadOS has used this internally for several years to implement various ancillary filesystems (like FAT), but macOS 15.4 is the first time it's been exposed as a supported API to 3rd parties.

Ooh! After 20 years does this mean we might finally get network filesystem implementations that don't stall out Mac OS whenever there is network lag?

Maybe not. The macFUSE issue suggests that networked file systems can be supported but some plumbing is missing.

https://github.com/macfuse/macfuse/issues/1025#issuecomment-...

This is big. Hopefully no more relying on macFUSE which is unmaintained and a pain to install and work with.

MacFUSE is well maintained and has regular releases. Apple silicon support is good, and I just installed an update a few days ago.

It does require a KEXT which requires lowering boot signing strength, which is annoying

Great, another step moving away from kexts into userspace alternatives.