v2.0

2026.10 F-Stack v2.0

1. F-Stack lib:

• Support single-process multi-thread mode (thread_mode=1).
• Add primary_slim mode, the primary keeps no rx/tx queue. Ref #1078.
• Add graceful_reload for nginx, HUP reload is lossless.
• Support lossless binary upgrade with USR2 under graceful_reload=1.
• Dispatch UDP flows across graceful reload.
• Add drain_ring_size, reload_heartbeat_timeout_ms and reload_udp_idle_ms in config.ini.
• Add idle_loop_interval in config.ini.
• Add ff_regist_idle_callback() and ff_unregist_idle_callback().
• Add LRO offload with software fallback, and improve TSO for IPv6.
• Support runtime MTU change and jumbo frames.
• Add mbuf water-level backpressure. Thanks @Sai-Raveendra-Kandregula
• Add fine-grained TX checksum offload control. Thanks @vincentmli
• Add extra_eal_args config option. Thanks @whatmatrix
• Add zero-copy receive ff_zc_recv(), and rework ff_zc_send() without the magic sentinel.
• Add FF_KERNEL_COEXIST for kernel stack coexistence.
• Optimize ff_rss_check() with rte_thash_adjust_tuple(), and support IPv6.
• Run RSS aware port selection for IPv6 outbound connects.
• Add ff_regist_packet_dispatcher_context(). @jinliu777
• Support nanosecond timestamp precision in pcap dump.
• Recognize IPv6 L4 checksum offload flags in ff_mbuf_tx_offload().
• Fix the BBR large-file hang.
• Add a cmocka based unit test framework.

1. adapter

• Add lock-free ring IPC for LD_PRELOAD (FF_USE_RING_IPC).
• Map Linux SO_TIMESTAMP to FreeBSD. @tarun-t
• Propagate the DPDK mbuf RX timestamp to the FreeBSD mbuf. @tarun-t
• Fix the ioctl conflicting types compile error on older glibc.
• Add an addrlen check in ff_hook_bind() (#1068).

1. FreeBSD

• Upgrade to FreeBSD-releng-15.0.
• Fix TCP timers never being armed (callout_when() was an empty stub).
• Fix EVFILT_TIMER precision of kqueue. Thanks @vanlink

1. ff tools

• Let the F-Stack tools find a stack by themselves (#419). @alberthaolihai
• Let ff_top and ff_traffic follow a graceful reload.
• Support cross-generation addressing with -p and -g.
• Fix IPFW crash when the rule list is large. Thanks @chocosnat
• Fix start.sh lcore_mask parsing to ignore commented lines.
• Fix ff tools build error with gcc-15.2.0 in ubuntu-26.04.

1. DPDK:

• Upgrade to DPDK-24.11.8(LTS).
• Fix the secondary process resetting the NIC (#860).
• Fix an infinite loop when a DPDK secondary process restarts. @jinliu777
• Fix the vmxnet3 rss_key_len in RSS mode. @WK-Tseng
• Fix build with GCC 15 and DPDK 25.11. @tarun-t
• Bump black, cryptography and pynacl in /dpdk/dts. @dependabot[bot]

1. APP

• Nginx: lossless reload (HUP) and binary upgrade (USR2).
• Nginx: dispatch UDP flows across reload.
• Nginx: fix a SIGSEGV in stream udp proxying.
• Nginx: add a reverse-proxy example with buffer settings.
• Redis: fix the build when the jemalloc configure script is missing (#802).

1. example

• Make helloworld thread-safe for thread_mode=1.
• Add a UDP echo server example (#1063).

1. doc:

• Add three-layer architecture docs and knowledge graph.
• Add F-Stack 2.0 preview blogs in Chinese and English.
• Update the nginx guide for graceful reload.
• Document the executable bits and symlink loss when the tree is copied from Windows.