Re: SATA hotplug not detecting new disks

From: Dave Hansen
Date: Fri Jul 26 2013 - 17:12:30 EST

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.


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. :)

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