On Wed, Aug 13, 2025 at 01:41:49PM -0700, Bart Van Assche wrote: > On 8/13/25 1:06 PM, Keith Busch wrote: > > But I can't make that change because many scsi devices don't set the dma > > alignment and get the default 511 value. This is fine for the memory > > address offset, but the lengths sent for various inquriy commands are > > much smaller, like 4 and 32 byte lengths. That length wouldn't pass the > > dma alignment granularity, so I think the default value is far too > > conservative. Does the address start size need to be a different limit > > than minimum length? I feel like they should be the same, but maybe > > that's just an nvme thing. > > Hi Keith, > > Maybe I misunderstood your question. It seems to me that the SCSI core > sets the DMA alignment by default to four bytes. From > drivers/scsi/hosts.c: Thanks, I think you got my meaning. I'm using the AHCI driver. It looks like ata_scsi_dev_config() overrides the dma_alignment to sector_size - 1, and that pattern goes way back, almost 20 years ago, so maybe I can't change it.
