What is needed in dsdt to enable S4(Besides \_S4)

[Bao, Zheng]

I have _S4 in my dsdt.asl.  But the dmesg only reports:

ACPI: (supports S0 S1 S2 S3 S5)

And cat /sys/power/state only says:

Standby mem

So what else is needed?

Thanks.

Zheng

[Tobias Diedrich]

Bao, Zheng wrote:
> I have _S4 in my dsdt.asl.  But the dmesg only reports:
>
> ACPI: (supports S0 S1 S2 S3 S5)
>
> And cat /sys/power/state only says:
>
> Standby mem

S4 is not used for suspend to disk in Linux AFAIK.
You just need to compile in suspend to disk support and specify a
resume partition on the kernel command line (Usually your swap
partition).

[Stefan Reinauer]

* Bao, Zheng  [110316 09:38]:
> I have _S4 in my dsdt.asl.  But the dmesg only reports:
>
> ACPI: (supports S0 S1 S2 S3 S5)
> So what else is needed?

I think you also need to add S4BIOS_REQ in the FADT and implement an SMM
handler to handle it.

You don't need that for software suspend to disk though

Stefan