ACPI S3 and VIA (C3) CPU

["Joel CARNAT" <joel%carnat.net@localhost>]

Hello,

I tried zzz(8) on my VIA machine (VIA Nehemiah) but got the error:
acpi0: entering state 3
acpi0: ACPI S3 not available on this platform
Using "sudo apm -S" just froze the machine.

It's running a GENERIC 4.99.72 kernel on top of a 4.99.63 userland.
I'm checking if it's worth upgrading the whole system (userland + pkgsrc)
to 4.99.72.

According to sysctl there is a suspend option:
# sysctl machdep
machdep.biosbasemem = 639
machdep.biosextmem = 457664
machdep.booted_kernel = netbsd
machdep.diskinfo: 80:156301488(1024/240/63),2  wd0:80
machdep.fpu_present = 1
machdep.osfxsr = 1
machdep.sse = 1
machdep.sse2 = 0
machdep.idle-mechanism = halt
machdep.acpi_vbios_reset = 1
machdep.acpi_beep_on_reset = 0
machdep.cpu_brand = VIA Nehemiah
machdep.sparse_dump = 1
machdep.tsc_freq = 1002365930
machdep.sleep_state = 0
machdep.acpiapm.standby = 1
machdep.acpiapm.suspend = 3

Is it possible to put this machine in sleep mode ?
Do I need a driver not enabled in GENERIC ?

TIA,
    Jo