Update readme

README.md

@@ -24,3 +24,75 @@ Or put it in /etc/fstab like:
 ```
 /local/cache/dir /where/you/want/it/mounted cachefs defaults,ro,allow_other,remote_dir=/remote/dir/to/cache,nofail,_netdev 0     0
 ```
+
+How to compile
+--------------
+
+If you have rust installed already, run the normal:
+`cargo build --release`
+
+If you don't, or if you need to compile for some ancient glibc, and have podman or docker, run:
+`podman run --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp docker.io/library/rust:1.62.1 bash -c 'apt-get update && apt-get -y install libfuse-dev && cargo build --release && strip target/release/cache-fs'`
+
+How to use it on the Steam Deck over NFS
+---------------------------------------
+
+There are many ways to set this up, personally I run `sudo systemctl start sshd` on the Deck and run all these commands
+via ssh from another computer, but that's optional, this is how I did it.
+
+(Optional): To speed first access up, you can pre-cache your filesystem on the NFS server, or from a computer with a faster
+(perhaps wired) connection by running `cache-fs -c /path/to/server/roms/dir/`, this will create a file `/path/to/server/roms/dir/cache-fs.tree.zst`
+which will be copied to the cache directory on first run instead of made by scanning the NFS share over Deck WiFi.
+
+Switch to desktop mode, install [EmuDeck](https://www.emudeck.com/) following instructions from there, copy your compiled
+`cache-fs` to `/home/deck/cache-fs` (I run `scp target/release/cache-fs deck@steamdeck:/home/deck/`) then run these
+commands, you'll need to re-run them again after any SteamOS update:
+
+```
+# create the directories to be mounted
+mkdir -p /home/deck/Emulation/{romsnfs,roms,roms-cache}
+
+# type your password to get a root console
+sudo -i
+
+# link the executable so mount.cachefs works
+ln -sf /home/deck/cache-fs /usr/bin/mount.cachefs
+# disable readonly fs
+steamos-readonly disable
+# initialize the pacman keyring
+pacman-key --init
+
+# these next 3 commands shouldn't be necessary but are, probably a bug to report to Valve...
+# this command will fail, press 'N' to not delete the package
+pacman -Sy archlinux-keyring
+# delete the signature file so we can install it anyway
+rm /var/cache/pacman/pkg/archlinux-keyring-*.pkg.tar.zst.sig
+# install the keys, press 'Y' to trust them
+pacman -U /var/cache/pacman/pkg/archlinux-*.pkg.tar.zst
+
+# finally install what we were after, nfs-utils that provide mount.nfs
+pacman -S --overwrite '*' nfs-utils
+```
+
+Now add the following to your `/etc/fstab`, I use run the command `nano /etc/fstab`, obviously replace IP and share with yours:
+```
+192.168.1.1:/mnt/deck/roms /home/deck/Emulation/romsnfs  nfs  defaults,ro,soft,timeo=100,retrans=0,retry=0,nodev,noexec,nosuid,noatime,async,v4,noauto,nofail,x-systemd.automount,x-systemd.mount-timeout=10,x-systemd.requires=NetworkManager.service,x-systemd.idle-timeout=1min,_netdev 0     0
+
+/home/deck/Emulation/roms-cache /home/deck/Emulation/roms cachefs defaults,ro,allow_other,remote_dir=/home/deck/Emulation/romsnfs,nofail,_netdev 0     0
+```
+
+Now you can reboot, or just run, (as root):
+```
+systemctl daemon-reload
+systemctl start home-deck-Emulation-romsnfs.automount home-deck-Emulation-roms.mount
+```
+
+You will now see all of your roms (the same network tree) in `/home/deck/Emulation/romsnfs` and `/home/deck/Emulation/roms`,
+but `/home/deck/Emulation/roms-cache` will be empty until the first file is accessed and it's copied there, start up
+EmulationStation and enjoy!
+
+How to use it a different way
+-----------------------------
+
+Send me other ways you use it, if your roms are accessible over http, running cache-fs over [rclone](https://rclone.org/commands/rclone_mount/)
+might be a great way to go, what else?