On Tue, 6 Apr 2021, Christoph Hellwig wrote: > > Last but not least I do hope you do not plan to retire ISA DMA bounce > > buffering support for drivers/block/floppy.c, as there is hardly an > > alternative available (I do have a single SCSI<->FDD interface built > > around an Intel 8080 CPU, in the half-height 5.25" drive form factor, but > > such devices are exceedingly rare, and then you need a suitable parallel > > SCSI host too). > > The floppy driver already uses its own bounce buffering for addressing > limitations, and only the kernel bounce buffering to avoid getting > fed highmem patches. Please take a look at this series to clean up the > latter: > > https://lore.kernel.org/linux-block/20210406061755.811522-1-hch@xxxxxx/T/#u Great, thanks! > > Would it be feasible to convert it and any other drivers for ISA DMA > > devices (like those support for which you propose to remove here) still > > have users who could verify operation to the IOMMU framework? > > I've converted the only once that still has signs of having users in > the last 10 or so years. I infer the answer is "yes" then. Of course it makes no sense to waste time and speculatively convert code nobody has expressed interest in and there's no immediate way to verify. Maciej
