On Thu, May 07, 2020 at 05:22:28PM +0200, Stefan Haberland wrote: > OK, just thought again about your suggestion and also that > you have already been talking about a symbol lookup I just > have written a prototype that took your first two patches > as base, exports the symbol of dasd_biodasdinfo and in > ibm.c I do a kallsyms_lookup_name("dasd_biodasdinfo"). > > So I would not have to define a structure twice or rely on > MAJORs. Also we would not have to define an own file > operation only for DASD devices. > > What do you think about this? If you agree I will polish > the patches, test them and send them for review. How do you figure out a given gendisk is a DASD device? I guess dasd_biodasdinfo could just check the block_device_operations pointer first thing. That's still a little ugly, but seems the least bad idea so far, so please at least post it for discussion.