STRUCT NPC_SUBBANK(9)

💅 struct npc_subbank(9) — a Kernel API Manual moment 🎀

okay so bestie, welcome to the Kernel API Manual page for struct npc_subbank — yes that's the manual name, and yes it's giving "you're about to read a struct definition and enjoy it." Let's go ✨

---

🌸 NAME 🌸

struct npc_subbank — literally just the subbank fields. That's the whole vibe. No cap.

---

✨ SYNOPSIS ✨

struct npc_subbank {
    u16 b0t, b0b, b1t, b1b;
    enum npc_subbank_flag flags;
    struct mutex lock;
    unsigned long b0map[BITS_TO_LONGS( MAX_SUBBANK_DEPTH)];
    unsigned long b1map[BITS_TO_LONGS( MAX_SUBBANK_DEPTH)];
    u16 idx;
    u16 arr_idx;
    u16 free_cnt;
    u8 key_type;
 };

look at her. iconic. absolutely no notes 🔥

---

🫶 Members 🫶

okay, member-by-member, and I'm gonna be so real with you about each one:

• b0t — subbanks top index for bank0. the top, bestie, the ceiling of bank0 👑
• b0b — subbanks bottom index for bank0. the floor, the basement, the b0b energy 🧚
• b1t — subbanks top index for bank1. same deal, but make it bank1 ⭐
• b1b — subbanks bottom index for bank1. the bottom of bank1, respectfully 💜
• flags — the subbank flags. the whole personality of this subbank lives here 🎀
• lock — a mutex lock guarding the flags and the rsrc modification. do NOT skip the lock, I'm serious 😭
• b0map — the bitmap map for bank0 indexes 🦋
• b1map — the bitmap map for bank1 indexes 🌈
• idx — the subbank index. her one true number 💅
• arr_idx — index into the free array or the used array. which one? that's between her and the code 🙈
• free_cnt — number of free slots in the subbank. keep an eye on it, she likes to go down 📉
• key_type — X4 or X2 subbank. that's the whole range, that's the whole choice ✨

---

💖 Description 💖

okay so here's the lore: the MCAM resource gets divided horizontally into multiple subbanks, and the resource allocation from each one of those subbanks is managed by this data structure. that's it, that's the plot 💀 literally every subbank out here being managed by this exact struct. main character energy fr fr.

---

🌟 SEE ALSO 🌟

go read these next, bestie, they're all in:

• the kernel file ./drivers/net/ethernet/marvell/octeontx2/af/cn20k/npc.h
• enum npc_subbank_flag(9)
• enum npc_dft_rule_id(9)
• struct npc_defrag_show_node(9)
• struct npc_priv_t(9)

iykyk 💅

---

🍓 friendly reminder: the manpage header says struct npc_subbank(9) and the manual is Kernel API Manual — now you can say you've been formally introduced 🫶

---

and that's the whole page, bestie!! this lil' rewrite comes straight out of ./drivers/net/ethernet/marvell... (yes the path literally ends in an ellipsis, we don't question the source 😭) and it's dated October 2026, so mark your calendar and stan responsibly. periodt. 👑✨