In CHI-B interface documentation, I am trying to find how does the CHI transaction convey user sideband information in the Request Flit. I see that there is a "RSVDC" field in the Request Flit. Can "RSVDC" field in the flit be used for conveying user sideband? If yes, the maximum width of the RSVDC bus is 32 (X = 32). Is 32 bit the maximum width of a sideband with CHI-B Interface supports?
Yes - RSVDC (Reserved for Customer Use) is the equivalent of User side band signalling.
As you've found, the maximum width allowed by the protocol is 32 bits.