Devices without power management support: dm0 dm1 (LVM / Device Mapper prevents ACPI Sleep State 3)

[Matthias Petermann <mp%petermann-it.de@localhost>]

Hello everybody,

I use NetBSD 9.0_RC1 and have configured the 2nd hard drive of my laptop 
(Lenovo X230) completely via LVM. Together with NVMM, that's a fine 
thing. What I noticed now, however, is that LVM (or the dm device) seems 
to be preventing my laptop from going into ACPI Sleep State 3 (suspend 
to RAM).

    x230Mk4# sysctl -a |grep acpi
    ....
    hw.acpi.sleep.beep = 0
    hw.acpi.sleep.vbios = 0
    hw.acpi.sleep.state = 0
    hw.acpi.sleep.states = S0 S3 S4 S5
    ....

    x230Mk4# sysctl -w hw.acpi.sleep.state=3
    hw.acpi.sleep.state: 0 -> 3

    x230Mk4# dmesg|tail -3
    [ 51617,201400] acpi0: entering state S3
    [ 51617,201400] Devices without power management support: dm0 dm1
    [ 51617,201400] acpi0: autoconfiguration error: aborting suspend

Is this problem known, or is it worth drilling deeper here? My first 
thought was - it can only be an accident. A logical layer like LVM 
doesn't have to be interested in power management. But I don't know 
enough about it to actually evaluate it. Nevertheless, the question: 
what speaks against implementing fake power management for LVM to enable 
suspend to RAM?

Best wishes
Matthias

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