From: Neth Iafin <NethIafin-obsd@proton.me>
Subject: Question - %gs support on OpenBSD
To: "tech@openbsd.org" <tech@openbsd.org>
Date: Tue, 29 Sep 2026 09:32:51 +0000

Hi OpenBSD,

I was wondering why OpenBSD has no ability to set %gs in userland?

Is this to avoid swapgs vulnerabilities? Something else?
I understand that supporting wine is probably below 0 on the priority list for OpenBSD, but I wonder about the reasoning behind %gs being locked to kernel.
I assume there is no chance that setting %gs will ever come back as a syscall?

Thanks,
Neth