scx_arena_to_kaddr(9)

💅 scx_arena_to_kaddr — from the Kernel API Manual (section 9, bestie)

okay so real talk, you're reading the scx_arena_to_kaddr(9) page, which lives in the Kernel API Manual, and it is genuinely one of the most useful little translators in the whole sched_ext situation. let me walk you through it 🫶

✨ NAME ✨

scx_arena_to_kaddr — the glow-up that turns a BPF-arena pointer into its actual kernel address 💫

🎀 SYNOPSIS 🎀

void * scx_arena_to_kaddr (struct scx_sched *sch , const void *bpf_ptr );

🌸 ARGUMENTS 🌸

• sch — the scheduler whose arena is hosting bpf_ptr. like, whose house is this pointer staying at 🏠
• bpf_ptr — the BPF-arena pointer itself. heads up: only the low 32 bits get used, bestie 👀

💖 DESCRIPTION 💖

so here's the tea ☕ — the (u32) cast is the main character here. it normalizes any input you throw at it into the arena's 4 GiB kern_vm range. no cap.

and when you pair that with scratch-page fault recovery? the returned pointer is safe to dereference up to GUARD_SZ / 2 past the intended object. iconic behavior, honestly 💅

but listen — if you need to access anything larger than GUARD_SZ / 2, you must explicitly bounds-check it yourself. this is not optional. don't let the vibe check catch you slipping 😭

🦋 SEE ALSO 🦋

Kernel file ./kernel/sched/ext/internal.h, plus the whole friend group:

• scx_add_event(9)
• __scx_add_event(9)
• struct scx_enable_args(9)
• struct sched_ext_ops(9)
• struct sched_ext_ops_cid(9)
• scx_kaddr_to_arena(9)
• DEFINE_SCX_COMPAT_MARKER(9)
• scx_root_protected_live(9)
• scx_root_protected(9)
• scx_bypass_dsp_enabled(9)
• scx_ops_sanitize_err(9)
• scx_has_subs(9)
• scx_task_sched(9)
• scx_task_sched_rcu(9)
• scx_task_on_sched(9)
• scx_prog_sched(9)
• scx_parent(9)

that's the whole page, bestie — you ate that 🍓 this gem came out of ./kernel/sched/ext in October 2026, so if anyone asks, that's the receipts 🔥 mwah 💋