Fedora 39 Looks To Boost vm.max_map_count To Help Windows Games With Steam Play

Written by Michael Larabel in Fedora on 24 April 2023 at 01:15 PM EDT. 24 Comments
Fedora 39 this autumn is looking at boosting its vm.max_map_count default to better match the behavior of SteamOS / Steam Deck and allowing more Windows games to run out-of-the-box with Steam Play.

The vm.max_map_count sysctl value controls the operating system limits on the maximum number of memory map (mmap) areas that a process can have. While Fedora's default of 65,530 for vm.max_map_count matches that of many other OS defaults, SteamOS Ships with a value of 2147483642 (MAX_INT - 5).

Most software doesn't use too many mmaps that the 65k default is suitably for the vast majority of user-space software out there. But in particular for a few Windows games running on Linux via Steam Play (Proton), that limit can actually be exceeded. Among the known games needing a higher memory map limit are DayZ, Hogwarts Legacy, Counter Strike 2, and others.

sysctl vm.max_map_count

A Fedora 39 change proposal has been filed and still needs to undergo the Fedora Engineering and Steering Committee (FESCo) review. The proposal is on lifting that vm.max_map_count limit to enhance compatibility with Windows games via Wine / Steam.

Thankfully it's super easy adjusting the vm.max_map_count value anyhow, so interested Linux gamers running Fedora can easily do so with a command such as sudo sysctl -w vm.max_map_count=2147483642.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

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