* Philippe Mathieu-Daudé ([email protected]) wrote: > 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.
Right. > 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... Or, you add a subsection which is conditional on MAX_FD > 2 and which only stores the state of the extra FDs. > Another option I don't like is: > > 3/ get ride of MAX_FD != 2 and clean the codebase... Seems sane to me. > $ 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? > > BTW this link is somehow interesting :) > https://www.seasip.info/VintagePC/floppies.html Ah interesting; I did wonder because I've never seen machines with more than 2 (double sided) drives. Dave > Thanks, > > Phil. -- Dr. David Alan Gilbert / [email protected] / Manchester, UK
