bpf_dynptr_memset(9)

💅 bpf_dynptr_memset(9) — the glow-up edition 🎀

okay so bestie, this is a page from the Kernel API Manual (section 9, the kernel-functions girlies 🌸) and it's all about one lil kfunc that fills memory with a byte. short page, huge slay. let's get into it ✨

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🌈 SYNOPSIS 🌈

like, here's the whole signature, verbatim, don't @ me:

__bpf_kfunc int bpf_dynptr_memset (const struct bpf_dynptr *p , u64
offset , u64 size , u8 val );

that's it. that's the whole vibe. 💖

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🫶 ARGUMENTS 🫶

• p — the destination dynptr, aka where the data is gonna get filled. this is the main character of the operation 👑
• offset — how far into the dynptr we start filling from. like, where the glow-up begins ✨
• size — how many bytes we're filling. the exact count, no cap 🔢
• val — the constant byte we're filling the memory with. one byte. iconic. 🍓

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💜 DESCRIPTION 💜

so what does it actually do? it fills size bytes of the memory area pointed to by p at offset with the constant byte val. literally that's the whole thing, and it ate 💅

and the returns? 0 on success, and a negative error otherwise. so if you get a negative number back, that's your sign that something went sideways 😭

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🔥 SEE ALSO 🔥

okay this is the part where the manpage just, like, lists every kernel file and its friends. and i mean every. we're talking:

Kernel file ./kernel/bpf/helpers.c — and then the whole squad:

bpf_obj_new(9), bpf_percpu_obj_new(9), bpf_obj_drop(9), bpf_percpu_obj_drop(9), bpf_refcount_acquire(9), bpf_list_push_front(9), bpf_list_push_back(9), bpf_rbtree_add(9), bpf_task_acquire(9), bpf_task_release(9), bpf_cgroup_acquire(9), bpf_cgroup_release(9), bpf_cgroup_ancestor(9), bpf_cgroup_from_id(9), bpf_task_under_cgroup(9), bpf_task_get_cgroup1(9), bpf_task_from_pid(9), bpf_task_from_vpid(9), bpf_dynptr_slice(9), bpf_dynptr_slice_rdwr(9), bpf_dynptr_copy(9), bpf_iter_bits_new(9), bpf_iter_bits_next(9), bpf_iter_bits_destroy(9), bpf_copy_from_user_str(9), bpf_copy_from_user_task_str(9), bpf_strcmp(9), bpf_strcasecmp(9), bpf_strnchr(9), bpf_strchr(9), bpf_strchrnul(9), bpf_strrchr(9), bpf_strnlen(9), bpf_strlen(9), bpf_strspn(9), bpf_strcspn(9), bpf_strstr(9), bpf_strcasestr(9), bpf_strnstr(9), bpf_strncasestr(9), bpf_lookup_user_key(9), bpf_lookup_system_key(9), bpf_key_put(9), bpf_verify_pkcs7_signature(9), bpf_task_work_schedule_signal(9), bpf_task_work_schedule_resume(9), bpf_timer_cancel_async(9)

whew. that's the whole friend group, no one left behind 🫶

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ngl bestie, this kfunc is simple but that's the point — fill size bytes at offset in p with val, get 0 back, and you're golden. anything negative means go check your vibes (and your args) 💀

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<div align="center">✨ that's the page! source file ./kernel/bpf, dated October 2026. mwah, go forth and memset responsibly, bestie 💅🎀💖</div>