Debian and exFAT

As some might have noticed we now have Linux 5.7 in Debian/unstable and subsequently the in kernel exFAT implementation created by Samsung available. Thus we now have two exFAT implementations, the exfat fuse driver and the Linux based one. Since some comments and mails I received showed minor confusions, especially around the available tooling, it might help to clarify a bit what is required when.

Using the Samsung Linux Kernel Implementation

Probably the most common use case is that you just want to use the in kernel implementation. Easy, install a Linux 5.7 kernel package for your architecture and either remove the exfat-fuse package or make sure you've version 1.3.0-2 or later installed. Then you can just run mount /dev/sdX /mnt and everything should be fine.

Your result will look something like this:

$ mount|grep sdb
/dev/sdb on /mnt type exfat (rw,relatime,fmask=0022,dmask=0022,iocharset=utf8,errors=remount-ro

In the past this basic mount invocation utilized the mount.exfat helper, which was just a symlink to the helper which is shipped as /sbin/mount.exfat-fuse. The link was dropped from the package in 1.3.0-2. If you're running a not so standard setup, and would like to keep an older version of exfat-fuse installed you must invoke mount -i to prevent mount from loading any helper to mount the filesystem. See also man 8 mount.

For those who care, mstone@ and myself had a brief discussion about this issue in #963752, which quickly brought me to the conclusion that it's in the best interest of a majority of users to just drop the symlink from the package.

Sticking to the Fuse Driver

If you would like to stick to the fuse driver you can of course just do it. I plan to continue to maintain all packages for the moment. Just keep the exfat-fuse package installed and use the mount.exfat-fuse helper directly. E.g.

$ sudo mount.exfat-fuse /dev/sdb /mnt
FUSE exfat 1.3.0
$ mount|grep sdb
/dev/sdb on /mnt type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096)

In case this is something you would like to make permanent, I would recommend that you create yourself a mount.exfat symlink pointing at the mount.exfat-fuse helper.

mkfs and fsck - exfat-utils vs exfatprogs

Beside of the filesystem access itself we now also have two implementations of tooling, which support filesystem creation, fscking and label adjustment. The older one is exfat-utils by the creator of the fuse driver, which is also part of Debian since the fuse driver was packaged in 2012. New in Debian is the exfatprogs package written by the Samsung engineers. And here the situation starts to get a bit more complicated.

Both packages ship a mkfs.exfat and fsck.exfat tool, so we can not co-install them. In the end both packages declare a conflict with each other at the moment. As outlined in this thread I do not plan to overcomplicate the situation by using the alternatives system. I do feel strongly that this would just create more confusion without a real benefit. Since the tools do not have matching cli options, that could also cause additional issues and confusion.

I plan to keep that as is, at least for the bullseye release. Afterwards it's possible, depending on how the usage evolves, to drop the mkfs.exfat and fsck.exfat from exfat-utils, they are in fact again only symlinks. pain point might be tools interfacing with the differing implementations. Currently I see only three reverse depedencies, so that should be manageable to consolidate if required.

Last but not least it might be relevant to mention that the exfat-utils package also contains a dumpexfat tool which could be helpful if you're more into forensics, or looking into other lower level analysis of an exFAT filsystem. Thus there is a bit of an interest to have those tools co-installed in some - I would say - niche cases.

buster-backports

Well if you use buster with a backports kernel you're a bit on your own. In case you want to keep the fuse driver installed, but would still like to mount, e.g. for testing, with the kernel exFAT driver, you must use mount -i. I do not plan any uploads to buster-backports. If you need a mkfs.exfat on buster, I would recommend to just use the one from exfat-utils for now. It has been good enough for the past years, should not get sour before the bullseye release, which ships exfatprogs for you.

Kudos

My sincere kudos go to:

Andrew Nayenko who wrote the exFAT fuse implemetation which was very helpful to many people for the past years. He's a great upstream to work with.
Namjae Jeon and Hyunchul Lee who maintain the Linux exFAT driver and exfatprogs. They are also very responsive upstreams and easy to work with.
Last but not least our ftp-master who reviewed the exfatprogs package way faster than what I had anticipated looking at the current NEW backlog.