[HELP] Shared Partition with Steam OS 3.2/Windows 10 Pro

[陸 - R I K U]

I currently have a 1tb nvme drive installed in my Steam Deck with both Steam OS and Windows 10 installed. I would like to use some of the storage space on this nvme as a shared drive between OSes for games.

I've attempted shrinking both OSes to be as small as possible and creating a btrfs partition using Gparted along with installing the btrfs driver for windows but I was unable to write to the partition in Steam OS.

I mount the partition at /var/mnt/

I run

sudo su

to get root then

chmod a=rwx /var/mnt/

and get no verbose

check permissions in dolphin and nothing changed and I'm unable to write to the btrfs partition

My other attempt was to create btrfs partition in KDE Partition Manager but I get an error that says the device already has 10 partitions and that is the max the partition table can handle. (Which is odd considering the situation with being able to mount and read when created with Gparted)

I'm not entirely new to Linux and how it works but I'm not experienced either. Any ideas or help from the masters out there?

[retrogunner]

You can do that sort of thing a bit more easily with a normal Linux distro & the standard Steam client as you control the OS layer features (such as 'apt install ntfs-3g fuse' or your distro's command equivalent.)

Creating a shared game space between both SteamOS 3.2 and Windows, I think YMMV given you're having to aim for the "lowest common denominator".

I've not seen anywhere the Steam Deck recognizes an NTFS formatted volume -- which is necessary given Windows doesn't recognize an EXT4 volume (which is must be formatted with the "casefold" option - which is a newer'ish option.)

Now, you might be able to set the OS Partition to read-write, then do 'sudo pacman -S ntfs-3g fuse' ... but ... you'll have to repeat that step after every SteamOS Update (which is happening pretty regularly and will continue for some time.)

Please be sure to share your findings other folks are interested in Dual Boot & Shared "SteamLibrary" directories.

Cheers. Retro

[陸 - R I K U]

Originally posted by retrogunner:

I've not seen anywhere the Steam Deck recognizes an NTFS formatted volume -- which is necessary given Windows doesn't recognize an EXT4 volume (which is must be formatted with the "casefold" option - which is a newer'ish option.)

Now, you might be able to set the OS Partition to read-write, then do 'sudo pacman -S ntfs-3g fuse' ... but ... you'll have to repeat that step after every SteamOS Update (which is happening pretty regularly and will continue for some time.)

Steam Deck definitely recognizes the NTFS partition of the Windows install and can mount it. In fact it mounts as a fuseblk filesystem but with read only attributes. Attempting to change to rwx with chmod results in an error saying that it can not be changed.

There is an ext4 read and write driver for windows however it gives issues with launching games as if they were launching from a network share that was no longer connected.

In my findings so far it seems it's only possible to share the SD card between the two OSes as I can setup btrfs as The Phawx has on SD cards and share that between them. Admittedly I feel like my inexperience in Linux is the reason I can't get this working.

[Prezidentas]

The whole dualbooting thing is iffy for now at best. SteamOS updater messes with partitions so I wouldn't do it while it's still not supported.
Windows locks its partitions because the default behavior for shutdown is partial hibernation. Try restarting from windows into SteamOS instead and see if it works (if you haven't tried that yet)..
You can also try running NTFS as a shared partition, though you would need this workaround to make games launch from it:
https://github.com/ValveSoftware/Proton/wiki/Using-a-NTFS-disk-with-Linux-and-Windows

[陸 - R I K U]

Originally posted by Red Star Gopnik:

The whole dualbooting thing is iffy for now at best. SteamOS updater messes with partitions so I wouldn't do it while it's still not supported.
Windows locks its partitions because the default behavior for shutdown is partial hibernation. Try restarting from windows into SteamOS instead and see if it works (if you haven't tried that yet)..
You can also try running NTFS as a shared partition, though you would need this workaround to make games launch from it:
https://github.com/ValveSoftware/Proton/wiki/Using-a-NTFS-disk-with-Linux-and-Windows

How would one restart from windows into Steam OS? I'm not using rEFInd just the standard bootloader.

I'll try this git you suggested but I'll say this. I'm not sure that ntfs-3g is installed by default and installing it would require read only file system being turned off and redone after every update I believe.

I wish they would have shipped with Kernal 5.16 instead of 5.13

[Prezidentas]

just click restart instead of shutdown

[陸 - R I K U]

Originally posted by Red Star Gopnik:

just click restart instead of shutdown

Yeah that sends me back into windows upon restart of the system. I'm going to assume that means I need to change boot priority in bios

[Prezidentas]

Originally posted by Riku Wayfinder:

Originally posted by Red Star Gopnik:

just click restart instead of shutdown

Yeah that sends me back into windows upon restart of the system. I'm going to assume that means I need to change boot priority in bios

what matters is you don't shut down from windows. alternatively when clicking "shut down" you can hold shift with your keyboard.

[陸 - R I K U]

For anyone interested my solution to this whole thing has been found!!!!

Debating on making a new thread as a tutorial for internal nvme partition sharing.

[Vass]

Originally posted by Riku Wayfinder:

For anyone interested my solution to this whole thing has been found!!!!

Debating on making a new thread as a tutorial for internal nvme partition sharing.

Hi there,
Found your thread and i'm in the same exact situation. Would you mind sharing your solution please ? Thanks

[retrogunner]

Please start a new thread so the title stands out and folks can talk/troubleshoot there.

I would recommend something with a leading tag like HOWTO, FYI, PSA, etc. Something like:
HOWTO Dual Boot SteamOS/Win10 with shared games directory
OR
FYI - How I share games on Deck between SteamOS and Win10

[⎛⎝Casket Pizza⎠⎞]

Sorry to necro this thread but this is the only one that appeared from a search, and since OP hasn't shared his solution:
For anyone finding this thread post-2023
The easiest way to do this is to shrink your windows partition with GParted to something small enough to hold just Windows and programs, then create a second NTFS partition for your Steam Library. SteamOS can write to and auto-mount a secondary NTFS partition.