This question is kind of theoretical, but I found no other StackExchange site to suite it better. I would like to know a little more about SMBUS and if it is possible to collect data from random PCI-E controller via SMBUS.
My current conclusions are:
- There are many brand servers with IPMI BMC being able to collect data from RAID controller (RAID just for example).
- IPMI have its own impression if RAID is happy and can display some details of what is happening.
- This connection is not working through PCI-E bus because this require intervention to the operating system, what is not happening.
- Any non-supported controller status will not be displayed so this protocol is vendor-specific. In fact I only know HP and IBM servers doing that.
- RAID utilities do not use SMBUS because sometimes we have to block SMBUS and they are still working.
This brings me to main questions:
- Is it right and SMBUS can be used for getting data from RAID controller status (or any other controller).
- What is the device SMBUS connected to? Does operating system have access to the bus or SMBUS is terminated on BMC and it is only BMC supporting that kind of protocols? What lm_sensors usually do - scan SMBUS or connect to BMC to know cached values of hardware status?
- Is there any vendor-specific or common protocol described anywhere. I can't find anything even close to that.
