tmpfs (Temporary File System) is a virtual filesystem to store files in memory.
The volatile memory can't keep the files after shutdown, reboot or crash. Only store recoverable files in tmpfs.
You need to activate the following kernel options:
File systems ---> Pseudo filesystems ---> [*] Tmpfs virtual memory file system support (former shm fs) [ ] Optional drivers
|Tmpfs POSIX Access Control Lists||Enable ACL permissions.|
|Tmpfs extended attributes||Enable metadata support.|
Generation and mounting of tmpfs is on step:
mount -t tmpfs tmpfs /MOUNTPOINT
You can specify the mount option size to control the maximum size of the filesystem (default: half of your memory). Note, that tmpfs doesn't reserve this memory, but allocates only the needed memory.