Re: RFC: ACPI/scsi/libata integration and hotswap

Matthew Garrett
2005-12-09T12:11:25Z

On Fri, Dec 09, 2005 at 06:58:41AM -0500, Jeff Garzik wrote:

> If this is for hotswap, as I noted, libata doesn't need this at all.
>
> If the hardware supports it, then libata will support it directly.
> There is no ACPI-specific magic, because ACPI does nothing but talk to
> the same hardware libata is talking to.

If libata knows how to talk to the random hardware attached to a Dell
laptop hotswap bay, I'll be amazed. Ejecting the drive generates a
system management interrupt, which then causes the ACPI code to check a
register in a block of machine-specific registers and generate an ACPI
notification. As far as I can tell, the controller has no say in the
matter at all - the Intel specs seem to suggest that ICH6 doesn't
generate a hotswap interrupt unless you're using AHCI (which this
hardware doesn't).

So, as far as I can tell, there /is/ ACPI-specific magic on
current-generation hardware. If we're lucky, they'll move to AHCI in
future and implement things properly there - but I wouldn't count on it.

--
Matthew Garrett | mjg59@srcf.ucam.org