Steam Machines no longer support a Suspend/Resume feature due to reliability issues, according to a report.
According to a post from Valve engineer JohnV over on GitHub, given the state of "hardware and software support" throughout the graphics stack on Linux, the firm didn't think it could make such a feature reliable.
Per Ars Technica, the issue stems from the way Linux handles "rediscovering hardware devices" upon being awoken from a sleep state. Some users report when peripherals such as USB controllers will become "completely unresponsive or lead to conflicts in discerning between multiple devices" in some cases.
The site points to a Slashdot post which explains the problem further, stating "suspend is not the problem, the problem is resume."
"It doesn't probe and reattach the controllers to the same point in the device tree that they were in when the system was suspended," reads the post. "Since those are the device nodes that SteamOS has open at the time of the suspend, and they route to The Noplace(tm), the controllers become unresponsive."
Suspend/Resume was a feature which launches with Xbox One and was added via a firmware update to PlayStation 4 back in March.