| filesystem | extended attributes | limit each | limit all | filename length | path length |
|---|---|---|---|---|---|
| ext4 | y | 4KiB | typically 4KiB | 255 B | - |
| btrfs | y | 4KiB | 255 B | - | |
| xfs | y | 256B / 64 KiB | 255 B | - | |
| ntfs | f | - | - | 255 B | 32767 B |
| hfs+ | y/f | 128 / 4KiB | 255 UTF-16 | - | |
| ufs | y | 255 B | - | ||
| zfs | y/f? | 255 B | - | ||
| ftp | n? | ||||
| sftp | n? | ||||
| smb | y? | ||||
| webdav | n? | ||||
| S3 | i | ||||
| dropbox | y/f | - | - | 260 | 260 |
| gdrive | n |
- y: extended file attributes available
- n: not available
- f: resource forks available
- i: implementation dependent
- ?: no reliable source found
All entries w/o question mark taken from either wikipedia extended file attributes or comparrison of file systems. Both pages don't have sources for most of the facts.