Alison Schofield wrote: > > + linux-cxl mailing list Thanks for forwarding...
> On Fri, Oct 11, 2024 at 05:58:52PM +0800, Coly Li wrote: > > Hi list, > > > > Recently I have a report for a warning message from CXL subsystem, > > [ 48.142342] cxl_port port2: Couldn't locate the CXL.cache and CXL.mem > > capability array header. > > [ 48.144690] cxl_port port3: Couldn't locate the CXL.cache and CXL.mem > > capability array header. > > [ 48.144704] cxl_port port3: HDM decoder capability not found > > [ 48.144850] cxl_port port4: Couldn't locate the CXL.cache and CXL.mem > > capability array header. > > [ 48.144859] cxl_port port4: HDM decoder capability not found > > [ 48.170374] cxl_port port6: Couldn't locate the CXL.cache and CXL.mem > > capability array header. > > [ 48.172893] cxl_port port7: Couldn't locate the CXL.cache and CXL.mem > > capability array header. > > [ 48.174689] cxl_port port7: HDM decoder capability not found > > [ 48.175091] cxl_port port8: Couldn't locate the CXL.cache and CXL.mem > > capability array header. > > [ 48.175105] cxl_port port8: HDM decoder capability not found > > > > After checking the source code I realize this is not a real bug, > > just a warning message that expected device was not detected. But > > from the above warning information itself, users/customers are > > worried there is something wrong (IMHO indeed not). > > > > Is there any chance that we can improve the code logic that only > > printing out the warning message when it is really a problem to be > > noticed? There is a short term fix and a long term fix. The short term fix could be to just delete the warning message, or downgrade it to dev_dbg(), for now since it is more often a false positive than not. The long term fix, and the logic needed to resolve false-positive reports, is to flip the capability discovery until *after* it is clear that there is a downstream endpoint capable of CXL.cachemem. Without an endpoint there is no point in reporting that a potentially CXL capable port is missing cachemem registers. So, if you want to send a patch changing that warning to dev_dbg() for now I would support that.
