STRUCT TB_NHI(9)

💜 NAME 💜

okay so bestie, struct tb_nhi is the thunderbolt native host interface, and this whole page is the struct tb_nhi(9) manual page from the kernel API manual. no cap, it's lowkey iconic. ✨

🎀 SYNOPSIS 🎀

struct tb_nhi {
    spinlock_t lock;
    struct device *dev;
    const struct tb_nhi_ops *ops;
    void __iomem *iobase;
    struct tb_ring **tx_rings;
    struct tb_ring **rx_rings;
    bool going_away;
    bool iommu_dma_protection;
    struct work_struct interrupt_work;
    u32 hop_count;
    unsigned long quirks;
    struct completion domain_released;
    bool host_reset;
 };

🌸 Members 🌸

• lock — bestie, this spinlock must be held during ring creation/destruction. it is also acquired by interrupt_work when dispatching interrupts to the individual rings. fr fr, it's the vibe-check bouncer for ring lifecycle. 💅
• dev — the device associated with this NHI instance. it's giving main character energy for this little NHI world. 🫶
• ops — NHI specific optional ops. optional? okay lowkey flexible, we love that. ✨
• iobase — MMIO space of the NHI. that's the literal hardware hangout spot. 🎀
• tx_rings — all Tx rings available on this host controller. slay, transmit side is booked and busy. 🔥
• rx_rings — all Rx rings available on this host controller. receive side is also thriving, periodt. 🌈
• going_away — the host controller device is about to disappear 😭 so when this flag is set, avoid touching the hardware anymore. like, do not poke the hardware when it's already leaving the group chat. 💀
• iommu_dma_protection — an IOMMU will isolate external-facing ports. protective queen behavior, honestly. 🛡️✨
• interrupt_work — work scheduled to handle ring interrupt when no MSI-X is used. it's the backup plan doing its little work moment. 💅
• hop_count — number of rings (end point hops) supported by NHI. literally the ring headcount, iykyk. 🎀
• quirks — NHI specific quirks if any. every family has its little quirks, no cap. 🙈
• domain_released — completed when domain has been fully released. the "we're so done here" completion, iconic. 🦋
• host_reset — Host router was reset on driver load, or forced on system shutdown/reboot. When set, tb_stop asserts DPR on connected downstream ports to signal disconnect before tearing down the router tree. Only Thunderbolt 3 devices are reset; USB4 routers are skipped. that's the whole rule, bestie, don't skip it. 👑

🌈 SEE ALSO 🌈

Kernel file ./include/linux/thunderbolt.h and the whole squad:

• enum tb_security_level(9)
• struct tb(9)
• struct tb_property_dir(9)
• struct tb_property(9)
• enum tb_link_width(9)
• struct tb_xdomain(9)
• struct tb_protocol_handler(9)
• struct tb_service(9)
• struct tb_service_driver(9)
• struct tb_ring(9)
• enum ring_desc_flags(9)
• struct ring_frame(9)
• tb_ring_rx(9)
• tb_ring_tx(9)
• tb_ring_dma_device(9)

source/version: ./include/linux · date: October 2026 · manual page: struct tb_nhi(9) 🌸🫶💖