Comment 14 for bug 292155

Okay, just did some ACPI debugging, as per the Ubuntu Wiki page about just that.

here is what I did:

Copied the debug instructions from wiki, added own comments: (it's all fairly clear)

Try booting with the "acpi=off" kernel parameter
This will disable ACPI support. If the error is the same with acpi enabled and disabled, this may not be an ACPI issue.
If "acpi=off" allows the system to boot, try to isolate the ACPI issue with the following boot parameters

Did that, boots fine then

Try booting with "acpi=ht"
This disables all of ACPI except just enough to enable Hyper Threading. If acpi=off works and acpi=ht fails, then the issue is in the ACPI table parsing code itself, or perhaps the SMP code.
Try booting with "pci=noacpi"
This disables ACPI for IRQ routing and PCI scanning.
Try booting with "acpi=noirq"
This disables ACPI for IRQ routing.

All the above make it boot fine.

Try booting with "pnpacpi=off"
This disables the ACPI component of the Linux Plug and Play code.
Try booting with "noapic"
Disables the IO-APIC for IRQ routing or PCI scanning.

Those two options make it boot, but same as original bug, need to press keys to force it to boot.

Try booting with "nolapic"
Disables the local APIC

Boot fails at:

"ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata3.00:qc timeout (cmd 0xec)
ata3.00: failed to IDENTIFY (I/O erroor, err_mask=0x4)"

that's the main thing, then it says "Gave up waiting for root device" and then lists common issues, etc.

Drops to Busybox.