"Best" (i.e. "universal") filesystem for portable USB drives?

aragats · Thursday at 7:16 PM

natterangell said:
Someone made a script

Just tried it, formatted a flash drive in MacOS, it works fine in MacOS, Linux and Windows. Doesn't work in FreeBSD. FreeBSD recognizes it as /dev/da0 (without partitions), but when trying mounting it I get:

Code:

mount_udf: /dev/da0: Invalid argument

[EDIT]
Linux's fdisk reports the partition as FAT32, Windows shows the correct UDF and FresBSD:

Code:

$ gpart show /dev/da0 
=>      63  30031809  da0  MBR  (14G)
        63  30031809       - free -  (14G)

covacat · Thursday at 9:37 PM

its most likely a sector size problem freebsd needs 2k for udf. and it is readonly anyway

aragats · Thursday at 11:40 PM

Regarding UDF: there is an old PR 120989 from 2008. A patch was submitted back in August 2026 for 15.X and 16-Current.

covacat · 2026-11-13T08:04:26+0000

aragats said:
Regarding UDF: there is an old PR 120989 from 2008. A patch was submitted back in August 2026 for 15.X and 16-Current.

i tried the patch from the PR and it seems to work. Tested it on a small disk image created on a mac.
Write support is not implemented so not very useful in thread's context.

covacat · 2026-11-13T10:08:08+0000

so the solution is simple, we switch to netbsd which has full UDF support

natterangell · 2026-11-13T11:40:25+0000

As a non-programmer, how difficult would it be to borrow the UDF-support from NetBSD and have it work in FreeBSD?
EDIT: What I mean is, what are the chances FreeBSD could implement it?

covacat · 2026-11-13T11:48:06+0000

to quote the guy who posted the patch on bugzilla "the write part is trickier". probably it can be done with AI help even by someone who is not a kernel fs programmer with some effort. the readonly part already works.

natterangell · 2026-11-13T12:18:31+0000

Just out of curiosity I looked into this some more. I also would prefer cross-compatibility between FreeBSD, OpenBSD, Windows, Linux and MacOS. Given UDF doesn't have rw support on FreeBSD, you're left with FAT32, exFAT and ext2. ext2 can work on all of these r/w. FreeBSD, OpenBSD and Linux you get native support unless you use some fancy features. Windows has free drivers available, MacOS does too (for Silicon Macs through open_ext4_for_mac, the Paragon proprietary driver for Intel Macs). That gets you 2TB file size limit given a 4K block size and a maximum filesystem of 16TB, and it supports ownership and permissions obviously. No journal though. Still, only FAT32 works across all these OSes natively.