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vms/windows: keep RDP VMs awake -- disable sleep in guest, fix the qemu global

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An idle Windows VM was suspending itself off the network after 15 min:
the Balanced power plan sleeps on idle, and the qemu S3/S4 disable was a
no-op -- `-global ICH9-LMB.disable_s3` is the wrong device class (q35's
bridge is ICH9-LPC), which qemu rejected as "invalid class name", so the
sleep states stayed on offer.

Fix both ends: correct the global to ICH9-LPC so the firmware stops
advertising S3/S4, and in post-oobe (any enableRDP image) switch to the
High Performance scheme, zero the standby/hibernate/monitor idle timeouts
and turn hibernate off -- a machine exposed as a service must not sleep.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0117qMyjpuXsjpVAcpJbFD8g
This commit is contained in:
Git Sagar 2026-09-18 10:39:49 -03:00
parent 1510b6c5ff
commit b7838f5501
2 changed files with 15 additions and 2 deletions
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10
lib/images/windows/templates/generalize.nix
View file

@ -544,6 +544,16 @@ in
reg add "HKLM\SYSTEM\CurrentControlSet\Services\SessionEnv" /v Start /t REG_DWORD /d 2 /f
reg add "HKLM\SYSTEM\CurrentControlSet\Services\UmRdpService" /v Start /t REG_DWORD /d 2 /f
reg add "HKLM\SYSTEM\CurrentControlSet\Services\TermService" /v Start /t REG_DWORD /d 2 /f
:: A VM reached over RDP must never suspend itself off the network. The
:: default Balanced plan sleeps after 15 min idle; switch to High
:: Performance and zero every idle timeout, and turn hibernate off.
powercfg /setactive SCHEME_MIN
powercfg /change standby-timeout-ac 0
powercfg /change standby-timeout-dc 0
powercfg /change hibernate-timeout-ac 0
powercfg /change hibernate-timeout-dc 0
powercfg /change monitor-timeout-ac 0
powercfg /hibernate off
''}
${lib.optionalString (staticIP != null || configMedium) ''

7
nixos/vms/config.nix
View file

@ -233,11 +233,14 @@ let
-machine type=${vmCfg.pc.type}${machineIrqchipArg} \
${optionalString vmCfg.bios.efi "-bios ${pkgs.OVMF.fd}/FV/OVMF.fd"} \
${optionalString vmCfg.bios.tpm "-chardev socket,id=chrtpm,path=/tmp/mytpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0"} \
${# Windows: localtime RTC, USB tablet for mouse, disable S3/S4 sleep
${# Windows: localtime RTC, USB tablet for mouse, disable S3/S4 sleep.
# The q35 power/LPC bridge is ICH9-LPC -- ICH9-LMB was a typo qemu
# rejects ("invalid class name"), so the sleep states stayed offered
# and an idle guest could suspend itself right off the network.
optionalString isWindows ''
-rtc base=localtime,clock=host \
-device qemu-xhci -device usb-tablet \
-global ICH9-LMB.disable_s3=1 -global ICH9-LMB.disable_s4=1 \
-global ICH9-LPC.disable_s3=1 -global ICH9-LPC.disable_s4=1 \
''} \
${optionalString hasOsDisk "-drive file=${osDiskPath},format=qcow2,if=virtio${optionalString (vmCfg.disks.os.persist == false) ",snapshot=on"}"} \
${optionalString (vmCfg.disks.iso.file != null) "-drive file=${toString vmCfg.disks.iso.file},media=cdrom,readonly=on"} \