Session Leader: bwidawsk

hackmd (content has been migrated to this page)

Previous Generation

• S1
• S2
• S3
• S4 - useful as BIOS reinits all hardware on resume

Opportunistic Idle (Runtime PM)

• power down USB devices, SATA, etc?
• We can switch PCI devices without drivers to D3, but this is disabled by default (hw.pci.do_power_nodriver=0) as it breaks things

Next Generation

• Intel's Low Power Idle (s0i1, s0i3 - aka s0ix)
  • Some systems going forward just don't support S3
  • S3 Emulation (Linux “suspend to idle”)
  • Opportunistic Idle
  • https://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf

turbostat is in ports, replacement for powertop

Known S3 Issues

• LCD on various laptops (often KMS fixes this)
• nvidia(4)
• em(4) on some systems does not survive resume (Thinkpad X220)
• Some Samsung nvd(4) drives will need nvme(4) code to suspend/resume successfully
• Some devices have broken timecounters on resume (either frozen, or racing)
• S4 may be useful as a base suspend/resume when S3 doesn't work