SATA hotplug notifications for BMC inventory updates

Johnathan Mantey johnathanx.mantey at
Thu Sep 8 00:04:48 AEST 2022

On 9/6/22 23:47, Konstantin Klubnichkin wrote:
> Hi Johnathan,
> What do you think about implementing this feature using SMI?
> Is it possible to raise SMI on drive plug/removal?

Paul, my experience with SMI is limited. Systems I've used that issued 
SMI only did so for PSUs. The details have gotten fuzzy over the years. 
I believe the SMI only asserted on removal of the power cord(s). The SMI 
event resulted in a high priority interrupt designed to tell the BMC to 
get state saved before complete power failure.

Even if you had the SMI connection from the HDD enclosure, I'm not 
certain how you'd acquire the information about which HDD was 
inserted/removed. That is an implementation detail of your HW.

A back of envelope thought I had is perhaps the host side could interact 
with the BMC via a mailbox. The issue being you'd have to have SW 
running during the BIOS time, and when the OS was in control an OS 
helper app pushing the data. I'm not sure how feasible that idea is.

> Thank you!
> 06.09.2022, 18:54, "Johnathan Mantey" <johnathanx.mantey at>:
>     On 9/5/22 04:11, Paul Fertser wrote:
>         Hi,
>         An OCP Tioga Pass platform features up to 4 drive bays for SATA
>         storage accessible from the front and fully hot-pluggable. The
>         backplane is usually connected directly to Intel C620 PCH (aka
>         Lewisburg).
>         It would be nice to have information about the currently attached
>         devices (model and serial number) available in BMC inventory but what
>         are the ways to get this information?
>     Intel systems only get drive mdl/sn from NVMe devices that provide
>     that information via MCTP over SMBus. SAS/SATA drives, to my
>     current knowledge, don't supply this info in that mode.
>     The insertion/removal events are also managed from the BMC via I2C
>     to a FPGA solution residing on the Hot Swap Backplane. The FPGA
>     provides registers that allow the BMC to query the PRSTn/IFDETn pins.
>         Is it possible there's some additional module in the all-mighty ME
>         that can supply BMC with the current state of PCH SATA controller? Or
>         is there some other sensible mechanism other than talking to UEFI on
>         startup (which would mean BMC is showing stale and thus misleading
>         data till the next reboot)?
>         Even though the question is quite specific we'd appreciate any related
>         insights on the topic; there must be some side-channels to RAID
>         controllers and such for BMC to be obtaining essential information but
>         so far I wasn't able to find any documentation about this.
>     RAID solutions are outside of scope for the Intel BMC.
>     --
>     Johnathan Mantey
>     Senior Software Engineer
>     *azad technology partners*
>     Contributing to Technology Innovation since 1992
>     Phone: (503) 712-6764
>     Email: johnathanx.mantey at
> -- 
> Best regards,
> Konstantin Klubnichkin,
> lead firmware engineer,
> server hardware R&D group,
> Yandex Moscow office.
> tel: +7-903-510-33-33
Johnathan Mantey
Senior Software Engineer
*azad te**chnology partners*
Contributing to Technology Innovation since 1992
Phone: (503) 712-6764
Email: johnathanx.mantey at
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the openbmc mailing list