Hervé Poussineau <[email protected]> writes: > Le 05/04/2019 à 12:29, Philippe Mathieu-Daudé a écrit : >> Hi, >> >> I am trying to understand the possible values for the MAX_FD variable >> used by the floppy controller model (hw/block/fdc.c). >> >> Looking at git history: >> >> - 2004-01-05 7138fcfbf7dd + 8977f3c107ef (Jocelyn Mayer): >> FDC introduced with "#define MAX_FD 2" >> >> - 2008-04-29 78ae820cfeb0 (Hervé Poussineau): >> Supports up to 4 floppy drives if MAX_FD is set to 4 >> Migration stream knows about runtime value of MAX_FD >> >> - 2009-09-10 d7a6c2703577 (Juan Quintela): >> FDC vmstate-ified >> Migration stream use compile time value of MAX_FD >> >> Since 7138fcfbf7dd MAX_FD has always been defined as 2. >> >> Since d7a6c2703577 MAX_FD can not be different than 2 without breaking >> migration. >> >> If I understand correctly migration, first we should change in >> vmstate_fdc the user-definable MAX_FD by a constant 2 value. >> >> Then to be able to use >2 floppy disks I have to modify the the >> vmstate.version_id, and >> >> 1/ add a new field in the vmstate_fdc containing the number of drives >> and add code to check >2 and adapt >> >> or >> >> 2/ change MAX_FD to 4 for all the codebase, adding some code to migrate >> to older FDC with only 2 disks... >> >> Another option I don't like is: >> >> 3/ get ride of MAX_FD != 2 and clean the codebase... >> >> $ git grep '#if MAX_FD' >> hw/block/fdc.c:744:#if MAX_FD == 4 >> hw/block/fdc.c:758:#if MAX_FD == 4 >> hw/block/fdc.c:1317:#if MAX_FD == 4 >> hw/block/fdc.c:1340:#if MAX_FD == 4 >> hw/block/fdc.c:2041:#if MAX_FD == 4 >> hw/block/fdc.c:2079:#if MAX_FD == 4 >> hw/block/fdc.c:2104:#if MAX_FD == 4 >> >> Hervé, what board are/were you using with 4 floppy drives? > > That was only an attempt to support 4 drives in code, as controller was able > to do it. > However, no emulated board took advantage of it, so that's why it kind-of > regressed. > > Feel free to choose the solution you prefer.
Since no user has appeared since 2008, it feels safe enough to assume that none will appear going forward. I lean towards your "3/ get ride of MAX_FD != 2 and clean the codebase..." Explain in a comment that we emulate only a 2-drive floppy controller, not the genuine IBM PC 4-drive floppy controller.
