Overview ======== Dummynet cannot directly configure link bandwidths above UINT32_MAX bits/s (4,294,967,295 bit/s). This prevents dummynet from shaping currently available multi-gigabit links at their full rates. My immediate use case is applying an FQ_CODEL limiter to an 8 Gbit/s residential Internet connection. Steps to Reproduce ================== On an unmodified FreeBSD main userland: # dnctl pipe 1 config bw 8Gbit/s dnctl: bandwidth too large Actual result ============= The command rejects bandwidth values above UINT32_MAX. Expected result =============== Dummynet should be able to configure and report link rates above UINT32_MAX, including an 8 Gbit/s rate, while retaining compatibility with existing userland and kernel interfaces where practical. Technical details ================= In the current source: * sbin/ipfw/dummynet.c:read_bandwidth() returns the parsed bandwidth through a uint32_t and rejects values greater than UINT_MAX. * sys/netinet/ip_dummynet.h defines struct dn_link.bandwidth as uint32_t. * The kernel scheduler state embeds struct dn_link, so the 32-bit representation is also carried into the kernel implementation. PR 194453 fixed the earlier signed 2 Gbit/s limit by changing the field to uint32_t, but this retained the current 4.29 Gbit/s ceiling: bug #194453 Design discussion ================= I started an RFC on freebsd-ipfw covering compatibility and ABI options, including a possible DN_LINK64 object, normalization into private 64-bit kernel state, API-version negotiation, and legacy GET behaviour: https://lists.freebsd.org/archives/freebsd-ipfw/2026-September/000623.html The precise ABI approach is intentionally left open pending feedback from the IPFW/dummynet maintainers. Work in progress ================ I have drafted an experimental implementation and ATF tests for UINT32_MAX, UINT32_MAX+1, 10 Gbit/s, and 100 Gbit/s, including FQ_CODEL. The implementation has not yet completed FreeBSD-CURRENT build and ATF validation, so I am not attaching it as a proposed patch yet. The implementation and tests will be submitted for formal review after the ABI direction has been discussed and they have been validated on FreeBSD-CURRENT.