Re: SATA hotplug not detecting new disks

[Dave Hansen <dave@sr71.net>]

On 07/25/2013 06:51 PM, Aaron Lu wrote:
> On 07/26/2013 07:15 AM, Dave Hansen wrote:
>> > I've got a relatively new system that doesn't seem to be able to hotplug
>> > SATA disks.  I see the same behavior on 3.10, 3.11-rc2, and Ubuntu's
>> > 3.8.0-25-generic.  The disks are detected right away on reboots, but
>> > even after poking the /sys/class/scsi_host/host*/scan files, new disks
>> > are never detected.  I've disabled link power management.
>> > 
>> > Am I doing something stupid here?  I thought this "just worked" on my
>> > previous hardware.
> My vague memory reminds me that not all SATA ports are hot pluggable -
> you can check the port's "External SATA port" bit and "Hot Plug Capable"
> bit of the PxCMD register like this:
> 
> $ grep ahci /proc/iomem 
>     e1a40000-e1a407ff : ahci
> # dd if=/dev/mem of=ahcidump bs=4096 count=1 skip=0xe1a40
> You will need to change 0xe1a40 to decimal format.
> 
> Then the PxCMD is at offset 0x118 for port 0, check bit 21 for E-SATA or
> bit 18 for hot pluggable bits. If any of them set to 1, this port
> should be hot pluggable; otherwise, it doesn't have this capability.

<sigh>

I went digging back through the BIOS settings, and found a nice checkbox
to enable hotplug support on the ports.  All seems happy now.

Thanks for the help.  I hope someone else googling will hit this thread. :)