[coreboot] How M2V-MX SE implemented the S4 sleep?

[Jiang Wang]

Hi there,

I am trying to understand how ASUS m2v-mx se implements S4 sleep. I
think it implemented this because I tested it on a physical machine
with coreboot and LINUX installed. And the machine can go to
hibernation and wake up without any problem.

Then I start to read the code. However, I only found following code in
mainboard/asus/m2v-mx_se/dsdt.asl:

/* For now only define 2 power states:
     *  - S0 which is fully on
     *  - S5 which is soft off
     * Any others would involve declaring the wake up methods.
     */
    Name (_S0, Package () { 0x00, 0x00, 0x00, 0x00 })
    Name (_S3, Package () { 0x01, 0x01, 0x00, 0x00 })
    Name (_S5, Package () { 0x02, 0x02, 0x00, 0x00 })

The above code said the board only supports s0 s3, and s5. So
something is missing? Why the Linux hibernation works but the code
said it only supports s3 and s5? Any suggestions? Thanks.

BTW: the comments for the code is wrong. The code also supports S3.
Also, I tested S3 on the same machine, but it turned out to be a
reboot. Is it a coreboot problem or Linux problem?

Regards,

Jiang