STRUCT DFL_FEATURE_INFO(9)

💖 struct dfl_feature_info — a kernel API manual moment, bestie 💖

okay so this is a page from the Kernel API Manual (the (9) girlies know), and it's all about struct dfl_feature_info — the little cutie that holds sub feature info collected during feature dev build. yes that's the NAME section, we're starting strong ✨

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🫶 SYNOPSIS 🫶

like, here's the whole struct, literally character for character, no notes:

struct dfl_feature_info {
    u16 fid;
    u8 revision;
    u8 dfh_version;
    struct resource mmio_res;
    void __iomem *ioaddr;
    struct list_head node;
    unsigned int irq_base;
    unsigned int nr_irqs;
    unsigned int param_size;
    u64 params[];
 };

it's giving "small but booked and busy" 💅

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🌸 Members 🌸

every single field, and what it's about — no skipping, we're thorough in this house:

• fid — id of this sub feature. it's the sub feature's whole identity fr fr 🪪
• revision — revision of this sub feature. the glow-up version number ✨
• dfh_version — version of Device Feature Header (DFH). yes, the header has its own version, main character energy 👑
• mmio_res — mmio resource of this sub feature. the actual memory-mapped turf 🗺️
• ioaddr — mapped base address of mmio resource. where the MMIO actually lives once it's mapped 🏠
• node — node in sub_features linked list. our girl is linked-list-ified, the way that she's on a list 😭
• irq_base — start of irq index in this sub feature. where the interrupt numbering begins 🔢
• nr_irqs — number of irqs of this sub feature. how many interrupts she brought to the party 🎉
• param_size — size DFH parameters. (yes, that's exactly how the original words it — keep it 💖)
• params — DFH parameter data. the flexible array member at the end doing the absolute most 🧚

ngl the params[] at the bottom with no size is iconic — it's a flexible array member, so the data just follows the struct. lowkey obsessed 🍓

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🔥 SEE ALSO 🔥

the whole friend group, and we're not leaving anyone out:

• Kernel file ./drivers/fpga/dfl.c — where a lot of this lives, go read it bestie 📖
• struct dfl_dev_info(9)
• struct dfl_chardev_info(9)
• dfl_fpga_port_ops_get(9)
• dfl_fpga_port_ops_put(9)
• dfl_fpga_port_ops_add(9)
• dfl_fpga_port_ops_del(9)
• dfl_fpga_check_port_id(9)
• dfl_fpga_dev_feature_uinit(9)
• dfl_fpga_dev_feature_init(9)
• dfl_fpga_dev_ops_register(9)
• dfl_fpga_dev_ops_unregister(9)
• struct build_feature_devs_info(9)
• dfh_find_param(9)
• parse_feature(9)
• dfl_fpga_enum_info_add_dfl(9)
• dfl_fpga_enum_info_add_irq(9)
• dfl_fpga_feature_devs_enumerate(9)
• dfl_fpga_feature_devs_remove(9)
• __dfl_fpga_cdev_find_port_data(9)
• dfl_fpga_cdev_release_port(9)
• dfl_fpga_cdev_assign_port(9)
• dfl_fpga_cdev_config_ports_pf(9)
• dfl_fpga_cdev_config_ports_vf(9)
• dfl_fpga_set_irq_triggers(9)
• dfl_feature_ioctl_get_num_irqs(9)
• dfl_feature_ioctl_set_irq(9)

like… that's the roster. 27 entries. we listed every single one because we don't do half-finished over here 💯

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and that's the page!! mwah 💋 this manual came from ./drivers/fpga and it's dated October 2026, so yeah, she's from the future and she's still serving struct realness. slay, stay hydrated, and go read your kernel source 🫶🌈⭐