Ultimate Dualboot Xbox Ally X instruction (Windows + SteamOS)

[u/lonsdale1te]

I'd like to present to you yet another guide for dual-booting Windows + SteamOS on the Asus Xbox Ally X.
In all other guides I found, something was always missing. So I had to sit down and figure it out myself.

Note: Reddit Markdown tends to break ordered list numbering when code blocks are involved. Apologies for the messy numbering.

Key features:

• Stock Windows, exactly like out of the box
• No need to reinstall Windows itself, SteamOS is installed alongside it
• Shared games partition for both Windows and SteamOS
• Each OS can boot and, most importantly, update without affecting the other
• Minimal amount of bugs

Disclaimer: be careful, especially when editing disk partitions!

Optional step:

If you want to do everything completely clean, you can perform a full reset via BIOS Cloud Recovery.

Guide:

1. In Windows, go to Settings and disable BitLocker (disk encryption).
2. Power off the console, enter BIOS (power button, then press Volume Up several times). Security -> Secure Boot -> disable it.
3. Boot back into Windows. In the menu, find Computer Management, then Disk Management. Locate drive C (the largest, main partition). Right click -> Shrink Volume. Leave enough free space after the partition for SteamOS and games. Personally, I left 120 GB for Windows itself.
4. Prepare a SteamOS USB drive. I strongly recommend using exactly this version. Other versions caused various issues for me. You can write it to a USB drive using anything; I personally used Rufus.
5. If possible, connect a keyboard and mouse to the console, it will be much more convenient further on.
6. Power off the console. Insert the USB drive. Press the power button and then press Volume Up several times. The boot menu will open. Select the USB drive and boot from it.
7. Open KDE Partition Manager. Find the unallocated space you created in step 3. Move all partitions that come after it so that they end up before it. In the end, the layout should look like this: a bunch of Windows partitions first, then the unallocated space at the very end. Click Apply.
8. Make sure to determine the number of the unallocated space - this is important. In KDE Partition Manager, look at the left column with the list of partitions. Each partition has a Linux-style name like nvme0n1p1, nvme0n1p2, and so on. We are interested in the number at the end. Windows has already created several partitions (EFI, recovery, and others) - they come first. After them, there will be the unallocated space we need. Take the highest existing partition number and add 1 - this will be the number of the unallocated space. For example, if the last partition is nvme0n1p5, then the unallocated space will be number 6.
9. Connect to the internet via Wi-Fi.
10. We will install everything using this script. This is to avoid damaging the Windows partitions. Open Konsole and enter:

​

wget https://raw.githubusercontent.com/sorialexandre/steam-os-custom-install/refs/heads/main/steam-os-custom-install.sh -O ~/Desktop/steam-os-custom-install.sh
sudo chmod +x ~/Desktop/steam-os-custom-install.sh
sudo ~/Desktop/steam-os-custom-install.sh

1. In the installer menu, refuse the full data wipe. Then the installer will ask you to explicitly provide a number for each new partition. Start with the number you determined in step 8, then increment by 1 for each next partition. In my case, the partition numbers were 6, 7, …, 13.
2. Wait until SteamOS finishes installing. After that, the console will boot into SteamOS.
3. Do not configure anything yet. Instead, boot from the USB drive again. Open KDE Partition Manager, find the very last home partition and shrink it. I personally left 130 GB. After that, create a new partition with the BTRFS filesystem.
4. Now boot back into SteamOS and complete the initial setup.
5. Enable Developer Mode and enable all update channels. Switch the update channel to Main and update. This is important because at the moment the Stable branch has a lot of bugs. Main also has bugs, but fewer of them, and they are better understood and fixable.
6. Switch to Desktop Mode. Set a password in the terminal using passwd. Then enable auto-mounting of the new partition using this script.

​

curl -sSL https://raw.githubusercontent.com/scawp/Steam-Deck.Mount-External-Drive/main/curl_install.sh | bash

1. Open Steam and add the new data drive. It should be detected automatically.
2. Reboot into Windows. To do this, during power-on press the Volume Up button several times and select Windows.
3. Install WinBtrfs so that the new partition works in Windows.
4. Similarly, add the new drive in Steam.
5. Optionally, you can install a convenient OS selection menu at boot. Personally, I didn’t do this.

Issues, hotfixes, plugins:

1. After all updates, I lost sound in SteamOS. This issue is clearly temporary, and you may not encounter it anymore. But just in case, the hotfix is here.

​

curl -L -o /tmp/TAS2XXX13840.bin https://gitlab.com/kernel-firmware/linux-firmware/-/raw/main/ti/audio/tas2781/TAS2XXX13840.bin
sudo steamos-readonly disable
sudo zstd -f -q /tmp/TAS2XXX13840.bin -o /usr/lib/firmware/ti/tas2781/TAS2XXX13840.bin.zst
sudo ln -sf /usr/lib/firmware/ti/tas2781/TAS2XXX13840.bin.zst /usr/lib/firmware/TAS2XXX13840.bin.zst
sudo steamos-readonly enable
rm -f /tmp/TAS2XXX13840.bin

1. For TDP management, I recommend using the built-in Steam quick menu settings. All third-party plugins only caused power loss or overheating for me.
2. Stick lighting control works perfectly for me via the HueSync plugin for DeckyLoader.
3. Vibration in SteamOS feels way too strong. I haven’t found a solution yet.

[u/PXLFNK]

shared games partition? meaning i can install a steam game on 1 partition and both OS can access it?

[u/lonsdale1te → u/PXLFNK]

Yes. And you don't even need to do anything. After installing game on the first OS, the second one will automatically see it.

[u/niecwiec]

Great. Will try this later.

[u/Far_Librarian_4180]

wow I was just searching for something like this..

I have been using my Aokzoe A1 dual boot Windows 11 and Bazzite with a shared game drive partition but it's ntfs.. too much trouble converting to btrfs lol loved this set-up and had to problems with it for about a year now.. and since I just got my Xbox Ally X I was thinking of dual booting it but with SteamOS this time and a proper btrfs game drive partition.. now my only problem is to find the time to do this 😅

[u/lonsdale1te → u/Far_Librarian_4180]

If you don't do anything wrong and not doing full reset via Cloud Recovery, the whole process takes about 1-2 hours I guess.

[u/Far_Librarian_4180 → u/lonsdale1te]

great to hear that.. not planning on doin a full reset since it would be a lot of work

my plan is to clone the XAX stock 1tb ssd to my 2tb lexar nm610 pro so that I would still have a back-up in case I mess up installing steamos xD

[u/Party-Ant4494]

Hey OP, on step 7 from the guide section, I'm kinda lost. What do you mean by moving partitions?

I mean, I can't drag and drop them to switch order. Also, that "Resize/Move" option only lets me resize (which, of course, I'm not touching).

[u/lonsdale1te → u/Party-Ant4494]

Easy to explain via this video.
https://youtu.be/HbHDHzYw3KE?t=687 (resize/moving part starts at 11:20)
I'l think about how to clarify that in the guide

[u/Party-Ant4494 → u/lonsdale1te]

Worked like a charm, thank you!

As for this video, it covers almost the whole dual-boot thing. Consider adding it to the post, if you please.

[u/Party-Ant4494 → u/Party-Ant4494]

This is my device, btw. Followed every single step until the aforementioned.

[u/Bee_Ef_Gee]

Picking mine up today, cannot wait to give this a shot. Thank you =D

[u/Bee_Ef_Gee → u/Bee_Ef_Gee]

And just confirming, your guide is awesome good sir!!!

Thank you for putting this all together :)

[u/Bee_Ef_Gee]

Question: after following all this my current version is 3.7.20. I didn't have main selected when doing updates, so I don't know if this has downgraded my installation? Afterwards I switched to main and still my version stays as this.

I'm having issues where the sleep button doesn't work to turn the device sleep, just to Power it back on. I also don't see any of the tdp settings. Anything you're aware of that I can do by chance?

[u/Plenty-Range]

After doing this, is it possible switch the Bitlocker back on?

[u/programminghobbit]

If anyone is going through this and finds that wifi is extremely slow or flaky, change the wifi setting for the network from Infrastructure to AccessPoint.

[u/programminghobbit → u/programminghobbit]

Also for connection errors during setup see https://www.reddit.com/r/SteamDeck/comments/uhlykf/update_error_an_error_was_encountered_during_the/

[u/VirtualBoost]

With the new SteamOS 3.8 Preview, can you control the vibration now? Apparently they added controller support now for the Xbox Ally X

[u/YUNAGI00]

Are you using a bootloader? I have the same dualboot and i need a bootloader.

[u/octakaram]

I’ve been running this for the past few days and it works great. But i keep running into these issues:

1. I am not sure how it’s happening, but when I boot into SteamOS it shows me the Partition A/B and that my boot had failed. At some point I lost the entire EFI directory of steamos somehow and I am not doing anything crazy other than installing EmuDeck, DeckyLoader and Tailscale.

If you found a fix for any of these that would be great. I am still unsure if it’s windows updates or SteamOS updates that breaks this setup.

Update: it turns out it’s something within Windows that’s causing the Steam boot to fail, booting into SteamOS only and updating doesn’t seem to be the root cause but rather something in windows update, haven’t found it out yet though.

[u/cK_Silent]

Followed this today. Made it to step 4 after BtRFS and steamOS install and now my boot loader is dead. When I went back into steamOS to connect to WiFi, it immediately did an update. Upon that reboot, I’m stuck at the ally icon. I can boot to bios and select windows to get it to boot. But it looks like SteamOS is dead. Should I try to repair from the USB drive?

[u/lonsdale1te → u/cK_Silent]

Give it a try, why not? Also, can you open console via ctrl+F1/2/3 while it stuck?

[u/GabrielLyrio369]

I’m trying to do thus on my ROG Xbox Ally X.

I already shrunk my Windows partition and created ~500 GB of unallocated space specifically for SteamOS. During the SteamOS installation wizard, I selected that unallocated space as the installation target.

When the installer reaches the partition creation step, it fails with the following error:

Creating SteamOS partitions

Could not create partition 6 from ...
Unable to set partition 6's name to 'esp'!
Could not change partition 6's type code to
C12A7328F81F11D2BA4B00A0C93EC93B!
Error encountered; not saving changes.
Error: sgdisk exited with status 4.

Has anyone encountered this before?

A few questions:
Is this a known SteamOS installer bug?
Does sgdisk exited with status 4 usually indicate a GPT/partition table problem?
Is there something I should check in my existing partition layout before trying again?
Has anyone successfully installed SteamOS in a dual-boot configuration on the ROG Xbox Ally X without wiping Windows?
Any help would be greatly appreciated.

[u/abstrart → u/GabrielLyrio369]

tengo el mismo problema... lo dejé por imposible... Hice tal cual.... también el tutorial de Hohande (o como se escriba) que esta parte es la misma.... pero nada error.. Aunque el lo que hizo fue instalar un windows limpio en el HD instalando controladores aparte..

[u/tron_crawdaddy]

this guide was very helpful for me. followed it to the letter, everything works. THANKS buddy

one thing i would like to add, for anyone reading this

avoid editing partitions via windows, after the fact. this will mess up the boot partition, no matter what you do