There's a real gem in that thread:

> FYI: There is also another cross-platform filesystem (Linux kernel, Windows NT kernel, Mac OS X kernel) suitable for hard disks too with POSIX permissions about which people do not know too much. It is UDF.

As I was struggling to find a way to share data between Linux/Windows with my gpu-passthrough setup, I'm excited to use this.

I think I've read something about 9p support in the latest Windows versions and I think QEMU supports 9p so that might become a good solution, too.

yrro

Sadly Microsoft and Apple have gone out of their way to make it difficult to access the same UDF filesystem from both Windows and macOS.

macOS will only access a UDF filesystem created on a disk device. Windows will only access one created inside a partition.

Linux, naturally, has no problem handling both. ;)

fulafel

A sibling comment linked https://github.com/JElchison/format-udf which claims that it creates a whole-device FS which works across all 3.