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

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.

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.