From: DaanDeMeyer <daan.j.demeyer@gmail.com>
Date: Thu, 17 Jul 2025 09:09:28 +0000 (+0200)
Subject: qemu: Disable hpet for x86 VMs
X-Git-Tag: v26~177
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0381b17819d9f2ece6ce97820b647c4b85d50cfb;p=thirdparty%2Fmkosi.git

qemu: Disable hpet for x86 VMs

hpet is an emulated clocksource that is generally discouraged in favor
of kvm-clock or tsc for virtual machines. While mkosi's virtual machines
already use kvm-clock, leaving hpet enabled causes qemu on the host to
consume a non-trivial amount of cpu, so let's disable the hpet feature since
we're not making use of it anyway.
---

diff --git a/mkosi/config.py b/mkosi/config.py
index f7cb8f863..16d613a40 100644
--- a/mkosi/config.py
+++ b/mkosi/config.py
@@ -554,6 +554,9 @@ class Architecture(StrEnum):
     def supports_smm(self) -> bool:
         return self.is_x86_variant()
 
+    def supports_hpet(self) -> bool:
+        return self.is_x86_variant()
+
     def can_kvm(self) -> bool:
         return self == Architecture.native() or (
             Architecture.native() == Architecture.x86_64 and self == Architecture.x86
diff --git a/mkosi/qemu.py b/mkosi/qemu.py
index 85b11eec1..a1377a16d 100644
--- a/mkosi/qemu.py
+++ b/mkosi/qemu.py
@@ -1214,6 +1214,8 @@ def run_qemu(args: Args, config: Config) -> None:
         machine += f",smm={'on' if firmware == Firmware.uefi_secure_boot else 'off'}"
     if shm:
         machine += ",memory-backend=mem"
+    if config.architecture.supports_hpet():
+        machine += ",hpet=off"
 
     cmdline: list[PathString] = []