mount_tmpfs(8) on Solnix vs Linux and the BSDs
On Solnix, mount_tmpfs(8) documents the illumos tmpfs mount, which you run through mount -F tmpfs with -o options such as size= and mode=. OpenBSD and NetBSD instead have a standalone mount_tmpfs with -g, -m, -n, -s and -u flags, and Solnix has none of those flags.
The manual pages
- Solnix: mount_tmpfs(8) from
pkgs.solnix.illumos-world-man· illumos.org - OpenBSD: mount_tmpfs(8) 8.0
- NetBSD: mount_tmpfs(8) 11.0
What Solnix runs
The bundle's header says the command on a default Solnix system is the illumos one, but its path is not in /usr/bin, /usr/sbin or /sbin. No other variants are shipped. The Solnix page documents the form mount [-F tmpfs] [-o specific_options] [-O] special mount_point, so it is a page about mount used with tmpfs, not a separate program with its own flags.
Differences
| Compared with | Topic | What differs |
|---|---|---|
| OpenBSD, NetBSD | invocation form | Solnix synopsis is mount [-F tmpfs] [-o specific_options] [-O] special mount_point. OpenBSD and NetBSD run mount_tmpfs directly with options such as -s size, and the literal word tmpfs as the device argument.Source: Solnix mount_tmpfs(8) SYNOPSIS; OpenBSD mount_tmpfs(8) SYNOPSIS; NetBSD mount_tmpfs(8) SYNOPSIS |
| OpenBSD, NetBSD | setting size | Solnix sets the size with -o size=sz. It accepts k, m, g suffixes and a % suffix, meaning a percentage of the swap space available to the zone. OpenBSD and NetBSD use -s size, where 0 is the default and means all available memory.Source: Solnix mount_tmpfs(8) OPTIONS size=sz; OpenBSD mount_tmpfs(8) -s; NetBSD mount_tmpfs(8) -s |
| OpenBSD, NetBSD | size suffix letters and case | Solnix size= suffixes are lowercase k, m, g and %. OpenBSD and NetBSD accept b, k, M and G in either case, for any numeric option. Source: Solnix mount_tmpfs(8) size=sz; OpenBSD mount_tmpfs(8) DESCRIPTION; NetBSD mount_tmpfs(8) DESCRIPTION |
| NetBSD | relative size notation | NetBSD -s also takes ram%n (a percentage of available system RAM) or ram/n (a fraction). The Solnix and OpenBSD pages document no such notation. Solnix size=N% is relative to the zone's available swap space, not RAM.Source: NetBSD mount_tmpfs(8) -s; Solnix mount_tmpfs(8) size=sz; OpenBSD mount_tmpfs(8) -s |
| OpenBSD, NetBSD | owner, group and mode of root | OpenBSD and NetBSD set the root inode's owner, group and mode with -u, -g and -m. Solnix has only a mode= option. Owner and group are inherited from the mount point where they can be determined. The page documents no way to override them.Source: Solnix mount_tmpfs(8) DESCRIPTION, mode=octalmode; OpenBSD mount_tmpfs(8) -u, -g, -m; NetBSD mount_tmpfs(8) -u, -g, -m |
| OpenBSD, NetBSD | inode/node limit | OpenBSD and NetBSD have -n nodes to cap the number of nodes. Both BUGS sections recommend it, because file system metadata is not pageable. The Solnix page documents no node limit.Source: OpenBSD mount_tmpfs(8) -n, BUGS; NetBSD mount_tmpfs(8) -n, BUGS; Solnix mount_tmpfs(8) OPTIONS |
| OpenBSD, NetBSD | overlay mount | On Solnix, mounting on an existing mount point fails with the error device busy unless -O is given. The OpenBSD and NetBSD pages have no -O and do not describe this behaviour.Source: Solnix mount_tmpfs(8) -O; OpenBSD mount_tmpfs(8) OPTIONS; NetBSD mount_tmpfs(8) OPTIONS |
| OpenBSD, NetBSD | remount | Solnix has a remount option that resizes the file system. A size not given with remount reverts to no limit. OpenBSD says updating mount options through mount -u is not supported. The NetBSD page does not say.Source: Solnix mount_tmpfs(8) remount; OpenBSD mount_tmpfs(8) CAVEATS |
| OpenBSD, NetBSD | special/device argument | Solnix: the special argument is usually swap but is disregarded. OpenBSD and NetBSD: the tmpfs argument exists only for compatibility with other mount commands and is ignored. Either way the word is not interpreted. Source: Solnix mount_tmpfs(8) DESCRIPTION; OpenBSD mount_tmpfs(8) DESCRIPTION; NetBSD mount_tmpfs(8) DESCRIPTION |
| OpenBSD, NetBSD | extended attributes and invalid options | Solnix accepts -o xattr or noxattr (default xattr). It prints a warning for invalid -o options and ignores them. OpenBSD and NetBSD refer to mount(8) for -o options, and the pages do not say how invalid ones are handled.Source: Solnix mount_tmpfs(8) -o, xattr | noxattr; OpenBSD mount_tmpfs(8) -o; NetBSD mount_tmpfs(8) -o |
| Linux | no Linux counterpart in bundle | The bundle has no Linux mount_tmpfs page, so nothing is claimed about how Linux mounts tmpfs. Source: Bundle header (counterparts: openbsd, netbsd only) |
| FreeBSD | no FreeBSD counterpart in bundle | The bundle has no FreeBSD mount_tmpfs page, so nothing is claimed about FreeBSD. Source: Bundle header (counterparts: openbsd, netbsd only) |
Standards
- POSIX: mount_tmpfs is not a POSIX.1-2024 utility.
Writing portable scripts
- Do not share one mount_tmpfs command line between Solnix and OpenBSD/NetBSD. Solnix: mount
-Ftmpfs-osize=... swap /mnt. OpenBSD/NetBSD: mount_tmpfs-ssize tmpfs /mnt. - Size suffixes differ: Solnix size= takes lowercase k, m, g or %. The BSDs take b, k, M, G in either case. Use plain byte counts for a size that works on all of them.
Every difference here is taken from the manual pages linked above: Solnix's published page, Linux (man-pages and the GNU and util-linux manuals), FreeBSD, OpenBSD and NetBSD. Each row names its source. Where a manual is silent, this page is too. Compiled 2026-10-26. Found a mistake? Mail hackers@lists.solnix.io.