STRUCT ETHTOOL_MM_STATS(9)

💖 struct ethtool_mm_stats(9) — the kernel API manual, bestie edition 💖

okay so real talk: this is a page from the Linux kernel API manual, and it's all about struct ethtool_mm_stats — aka the 802.3 MAC merge layer statistics struct. yes it's a mouthful, no you don't have to say it out loud. it's giving "niche but iconic" ✨

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🌸 NAME 🌸

struct ethtool_mm_stats — 802.3 MAC merge layer statistics</p> 🎀

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✨ SYNOPSIS ✨

here's the whole glow-up of the struct, and yes you're gonna copy it exactly, no freestyling:

struct ethtool_mm_stats {
    u64 MACMergeFrameAssErrorCount;
    u64 MACMergeFrameSmdErrorCount;
    u64 MACMergeFrameAssOkCount;
    u64 MACMergeFragCountRx;
    u64 MACMergeFragCountTx;
    u64 MACMergeHoldCount;
 };

six u64 fields, all of them locked in, all of them counting something. slay 💅

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🦋 Members 🦋

bestie, this is the part where we go field by field and i tell you what each one is actually keeping track of. the way that these counters are all received or sent or state changes is honestly so coherent. obsessed 🫶

• MACMergeFrameAssErrorCount — received MAC frames with reassembly errors 😭 (yeah, things went wrong, and this is the receipt)
• MACMergeFrameSmdErrorCount — received MAC frames/fragments rejected due to unknown or incorrect SMD 🙈 (SMD said no ❌)
• MACMergeFrameAssOkCount — received MAC frames that were successfully reassembled and passed up 💖 (the good timeline, congrats to them)
• MACMergeFragCountRx — number of additional correct SMD-C mPackets received due to preemption 🌈 (additional is doing so much work in that sentence and i respect it)
• MACMergeFragCountTx — number of additional mPackets sent due to preemption 🚀
• MACMergeHoldCount — number of times the MM layer entered the HOLD state, which blocks transmission of preemptible traffic ✋💀 (it literally holds the traffic, hence the name — iykyk)

ngl the "HOLD state, which blocks transmission of preemptible traffic" part is the one to remember. it's not a vibe, it's a blocker. literally.

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🔥 SEE ALSO 🔥

the kernel file ./include/linux/ethtool.h and honestly a whole friend group of related symbols — here they all are, no gatekeeping, no cap:

• enum ethtool_phys_id_state(9)
• struct kernel_ethtool_ringparam(9)
• enum ethtool_supported_ring_param(9)
• ethtool_rxfh_indir_default(9)
• struct ethtool_rxfh_context(9)
• ethtool_link_ksettings_zero_link_mode(9)
• ethtool_link_ksettings_add_link_mode(9)
• ethtool_link_ksettings_del_link_mode(9)
• ethtool_link_ksettings_test_link_mode(9)
• ethtool_intersect_link_masks(9)
• struct ethtool_phy_stats(9)
• struct ethtool_pause_stats(9)
• struct ethtool_fec_hist_range(9)
• struct ethtool_fec_stats(9)
• struct ethtool_rmon_hist_range(9)
• struct ethtool_rmon_stats(9)
• struct ethtool_ts_stats(9)
• struct ethtool_module_eeprom(9)
• struct ethtool_module_power_mode_params(9)
• struct ethtool_mm_state(9)
• struct ethtool_mm_cfg(9)
• struct ethtool_mmsv_ops(9)
• struct ethtool_mmsv(9)
• struct ethtool_rxfh_param(9)
• struct ethtool_rxfh_fields(9)
• struct kernel_ethtool_ts_info(9)
• struct ethtool_ops(9)
• struct ethtool_netdev_state(9)
• struct ethtool_phy_ops(9)
• ethtool_set_ethtool_phy_ops(9)
• ethtool_params_from_link_mode(9)
• ethtool_get_phc_vclocks(9)
• ethtool_mm_frag_size_add_to_min(9)
• ethtool_mm_frag_size_min_to_add(9)
• ethtool_get_ts_info_by_layer(9)
• ethtool_sprintf(9)
• ethtool_puts(9)
• ethtool_cpy(9)

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and that's the whole page, bestie 💜✨

cute little sign-off for the citation girlies: this one lives over in ./include/linux, it's dated October 2026 🌸, and it's filed under the manual name struct ethtool_mm_stats(9) — mwah, periodt 💅🎀