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 f7cb8f8637443a8e6731ba10c68d50a906620d6b..16d613a40fbe467ee31f8b113a0755698aa80819 100644 (file)
--- 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 85b11eec19ebd34d41eeb2d869d1383361ba1de9..a1377a16d13ce662ea826cbfb317772478a1cf85 100644 (file)
--- 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] = []