On Mon, Sep 23, 2019 at 10:43 PM Andriy Gapon <a...@freebsd.org> wrote: > > > It seems that the userland component of ipfw/dummynet uses int for the > bandwidth > represented in bit/s. Also, int is used for passing that value from the > userland to the kernel. > > What would be the best way to extend this? > Just use a larger type? > Or maybe add another field to try to preserve KBI backward compatibility?
As others have commented changing the ABI is a no-go. However the command structure can be extended: - define a new type, say DN_LINK64, and a new struct dn_link64 with a 64-bit bw field; - modify the kernel to accept the new type in addition to DN_LINK to set link speed, and reply with DN_LINK64 for links whose bandwidth cannot be represented on 31 bits (these must come from a userland that understands the new format, so it is reasonable to reply to queries with those) - modify the ipfw libraries to, likewise, understand DN_LINK64 on queries, and issue DN_LINK64 when bw requests do not fit on 31 bits (on failure). An alternate, hack-ish approach would be to encode high speeds with coarse granularity, say speed 0x7fnnnnnn with n = 0.. 0xffffe representing speed in Mbits/s (so that would give you up to 16 Pbit/s) and reserve 0x7fffffff for the pre-existing "2Gbit/s - 1" to avoid breaking former userland that may pick that value. cheers luigi that uses an extended field size for length. One thing that could be done is _extend_ the ABI > > Thank you. > -- > Andriy Gapon > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" -- -----------------------------------------+------------------------------- Prof. Luigi RIZZO, ri...@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL +39-050-2217533 . via Diotisalvi 2 Mobile +39-338-6809875 . 56122 PISA (Italy) -----------------------------------------+------------------------------- _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
