STRUCT ETHTOOL_RX_FLOW_SPEC(9)

💅 struct ethtool_rx_flow_spec(9) — Kernel API Manual ✨

okay bestie, welcome to the iconic little struct that tells your NIC "hey, when a packet looks like this, put it over there". it's giving traffic-cop but make it kernel ✨ (this is from the Kernel API Manual, by the way — keep that energy 🫶).

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🎀 NAME 🎀

struct ethtool_rx_flow_spec — the classification rule for RX flows. like, a whole lil bouncer for your incoming packets 💅

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🌸 SYNOPSIS 🌸

struct ethtool_rx_flow_spec {
    __u32 flow_type;
    union ethtool_flow_union h_u;
    struct ethtool_flow_ext h_ext;
    union ethtool_flow_union m_u;
    struct ethtool_flow_ext m_ext;
    __u64 ring_cookie;
    __u32 location;
 };

ngl, look at that struct. absolutely ate. 🔥

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🦋 Members 🦋

okay so let's go through the members one by one, no skipping, we don't do that here 💖

• flow_type — the type of match you're doing, e.g. TCP_V4_FLOW. this is the main-character field, it decides everything else 🌈
• h_u — the actual flow fields to match. which fields? honestly depends on flow_type — it's giving "read the room" 🧚
• h_ext — the additional fields to match, for when the regular ones just aren't enough 💅
• m_u — masks for the flow field bits you want matched (yes, masks, we love a good bitmask era) 🎀
• m_ext — masks for the additional field bits to be matched. important, bestie: all the additional fields have to be ignored unless flow_type includes the FLOW_EXT or FLOW_MAC_EXT flag — go read the struct ethtool_flow_ext description, it says it right there, iykyk 🙈
• ring_cookie — the RX ring/queue index to deliver to. orrr it can be RX_CLS_FLOW_DISC if the packets should just be discarded (bye 👋), or RX_CLS_FLOW_WAKE if the packets should be used for Wake-on-LAN with WAKE_FILTER (waking up is highkey a vibe ⭐)
• location — where the rule sits in the table. and here's the caveat bestie, listen: locations must be numbered so that a flow matching multiple rules gets classified according to the first (lowest numbered) rule. lowest number wins, periodt 👑

lowkey do not sleep on that location ordering rule. multiple matches → lowest number takes it. no cap. 💀

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✨ SEE ALSO ✨

the whole extended friend group 💜 — starting with the kernel file itself:

• Kernel file ./include/uapi/linux/ethtool.h
• struct ethtool_cmd(9)
• struct ethtool_drvinfo(9)
• struct ethtool_wolinfo(9)
• struct ethtool_regs(9)
• struct ethtool_eeprom(9)
• struct ethtool_eee(9)
• struct ethtool_modinfo(9)
• struct ethtool_coalesce(9)
• struct ethtool_ringparam(9)
• struct ethtool_channels(9)
• struct ethtool_pauseparam(9)
• enum ethtool_stringset(9)
• enum ethtool_mac_stats_src(9)
• enum ethtool_module_power_mode_policy(9)
• enum ethtool_module_power_mode(9)
• enum ethtool_c33_pse_ext_state(9)
• enum ethtool_c33_pse_ext_substate_mr_mps_valid(9)
• enum ethtool_c33_pse_ext_substate_error_condition(9)
• enum ethtool_c33_pse_ext_substate_mr_pse_enable(9)
• enum ethtool_c33_pse_ext_substate_option_detect_ted(9)
• enum ethtool_c33_pse_ext_substate_option_vport_lim(9)
• enum ethtool_c33_pse_ext_substate_ovld_detected(9)
• enum ethtool_c33_pse_ext_substate_power_not_available(9)
• enum ethtool_c33_pse_ext_substate_short_detected(9)
• enum ethtool_pse_types(9)
• enum ethtool_c33_pse_admin_state(9)
• enum ethtool_c33_pse_pw_d_status(9)
• enum ethtool_podl_pse_admin_state(9)
• enum ethtool_podl_pse_pw_d_status(9)
• enum ethtool_mm_verify_status(9)
• enum ethtool_module_fw_flash_status(9)
• struct ethtool_gstrings(9)
• struct ethtool_sset_info(9)
• enum ethtool_test_flags(9)
• struct ethtool_test(9)
• struct ethtool_stats(9)
• struct ethtool_perm_addr(9)
• struct ethtool_tcpip4_spec(9)
• struct ethtool_ah_espip4_spec(9)
• struct ethtool_usrip4_spec(9)
• struct ethtool_tcpip6_spec(9)
• struct ethtool_ah_espip6_spec(9)
• struct ethtool_usrip6_spec(9)
• struct ethtool_flow_ext(9)
• struct ethtool_rxnfc(9)
• struct ethtool_rxfh_indir(9)
• struct ethtool_rxfh(9)
• struct ethtool_rx_ntuple_flow_spec(9)
• struct ethtool_rx_ntuple(9)
• struct ethtool_dump(9)
• struct ethtool_get_features_block(9)
• struct ethtool_gfeatures(9)
• struct ethtool_set_features_block(9)
• struct ethtool_sfeatures(9)
• struct ethtool_ts_info(9)
• struct ethtool_per_queue_op(9)
• struct ethtool_fecparam(9)
• enum ethtool_fec_config_bits(9)
• struct ethtool_link_settings(9)
• enum phy_upstream(9)

that's the whole squad. go read them. or don't, i'm not your mom 🍓

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kay that's the page bestie!! 💖 this one lives in ./include/uapi/linux, dated October 2026, and it's filed under struct ethtool_rx_flow_spec(9) — mwah, slay, see u in the next man page 🧚‍♀️✨