Christoph, for Atari SCSI, commands can only be merged if the physical addresses of all buffers are contiguous (limitation of the Falcon DMA engine). Documentation/scsi/scsi_mid_low_api.tx does not spell out whether that is the case. Atari SCSI disables scatter/gather, so if that's sufficient to cue midlevel or bio to not undertake any merging, the flag is no longer needed. Cheers, Michael On Wed, Nov 21, 2018 at 10:41 PM Christoph Hellwig <hch@xxxxxx> wrote: > > Hi all, > > you in the To list maintain or wrote SCSI drivers that set the > DISABLE_CLUSTERING flag, which basically disable merges of any > bio segments. We already have the actual max_segment size limit > to say which length a segment should have, independent of merged > or originally created, so this limit generally should rarely if > ever be required, and mostly is an old cut an paste error. > > Can you go over your drivers and check if it could be removed?