Aufs not available for kernel 5.8 Can dbp switch to OverlayFS?

[clort81]

Hello slaeshjag. I see several years have passed since your .dbp work began.

aufs is apparently not available for my kernel 5.8. I do not know how to build it.

Since OverlayFS is available and appears functionally equivalent, perhaps this is the time to switch .dbp to using it and enabling .dbp to work on other kernels.

Thank you.

[EDIT]
Seems this isn't a big deal to switch to non-aufs after all?

libdbpbase/loop.c:      if (mount("none", mount_path, DBP_UNIONFS_NAME, 0, mount_opt) < 0)
libdbpbase/dbp.h:#define        DBP_UNIONFS_NAME        "aufs"

[EDIT2]
a reference for doing it with unionfs
unionfs merge-mount

[slaeshjag]

OverlayFS was considered at first, primarily because it's already part of the kernel.

The reason for using aufs, is due to a requirement that the writes can be redirected to an SD card formatted with FAT/exFAT/NTFS. Last time OverlayFS was considered, which was around 2016 iirc, this was not possible. I don't remember the specifics, but urjaman vaguely remembered it had something to do with xattrs.

Unless this has changed, it is not really an option. One of the main points of this system is to simplify loading large applications off external media, and these users will most probably not use a sane file system.

Do you have any further insights into this?

[clort81]

can be redirected to an SD card formatted with FAT/exFAT/NTFS. L

I hadn't thought about the FAT/exFAT requirement. Thanks for the reply.

I'll sniff around a bit to see if I can get OverlayFS to union mount FAT/exFAT.

Do you know how to get aufs working with newer kernels? Unhappy situation, it seems.

[clort81]

After learning more about OverlayFS, the big difference to aufs is that the union mount is designed to have either the 'upper' or 'lower' FS be read-only for those processes, but not both.

It seems to me that the pnd/dbp cartridge-like scheme from the old Pandora with a very barebones and fairly fixed host OS doesn't translate without complication to the more full-featured pyra-OS environment.

The current aufs-union mounted .dbps schema is that dbps are more like full-featured debs, with added extras like screenshots and repository goodies. However, their ability to modify/interact with the root filesystem also means you can't pop them into another pyra or an upgraded system while expecting them to keep working.

An alternative approach for dbps that eliminates dependency on aufs would be two types of Pyra-optimized apps

1. .dbps for games and emulators requiring limited state preservation -- these could run in a union (aufs or overlayfs), and save state within the .dbp without modifying root filesystem and thus be fairly portable between devices and OS-installs.

2. .debs for apps that interact with the root filesystem, sourced from a pyra debian repository.

Neither approach is objectively better, it all depends on design goals and the intended scope for the .dbp format.

[Cloudef]

https://git.cloudef.pw/pacbox.git/tree/pacbox.sh#n33 I used unionfs to achieve the same effect as aufs in this pacman sandboxer toy before (note this uses fuse!)