on 18/04/2012 17:40 Ian Lepore said the following: > On Wed, 2012-04-18 at 17:36 +0300, Andriy Gapon wrote: >> on 18/04/2012 17:22 Ian Lepore said the following: >>> YES! A size field (preferably as the first field in the struct) along >>> with a flag to indicate that it's a new-style boot info struct that >>> starts with a size field, will allow future changes without a lot of >>> drama. It can allow code that has to deal with the struct without >>> interpretting it (such as trampoline code that has to copy it to a new >>> stack or memory area as part of loading the kernel) to be immune to >>> future changes. >> >> Yeah, placing the new field at front would immediately break compatibility >> and >> even access to the flags field :-) >> > > Code would only assume the new field was at the front of the struct if > the new flag is set, otherwise it would use the historical struct > layout.
Right, but where the flag would reside? And how the older code that is not aware of the new flag would cope with the new layout? -- Andriy Gapon _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
