i915_perf_open_ioctl(9)

💅 i915_perf_open_ioctl(9) — like, the kernel API manual, bestie ✨

okay so before we even start — this whole page lives in the Kernel API Manual, and the star of the show is i915_perf_open_ioctl(9). yes the title is a mouthful, no we're not renaming it, it's iconic as-is 🎀

---

🌸 NAME 🌸

i915_perf_open_ioctl — the DRM ioctl() that lets userspace open a stream FD 🦋

---

✨ SYNOPSIS ✨

int i915_perf_open_ioctl (struct drm_device *dev , void *data , struct
       drm_file *file );

literally the whole signature, no cap 💅

---

🫶 ARGUMENTS 🫶

• dev — the drm device 👑
• data — the ioctl data, copied over from userspace and not validated yet (so, like, treat it with suspicion until further notice 🙈)
• file — the drm file 🍓

---

💖 DESCRIPTION 💖

so what this does is validate the stream open parameters that userspace handed over — that includes the flags and an array of u64 key, value pair properties. vibe check first, streaming second ✨

and here's the cute part: we assume, like, very little up front about what kind of stream is being opened. for instance, we don't assume it's for periodic OA unit metrics. an i915-perf stream is expected to be a suitable interface for other forms of buffered data written by the GPU besides periodic OA metrics — so it's giving main character energy for more than just one use case 💅

lowkey important note, bestie: we copy the properties from userspace outside of the i915 perf mutex, and that's on purpose — it avoids an awkward lockdep situation with mmap_lock 😭 so don't come for that ordering, it's deliberate.

most of the actual implementation details are handled by i915_perf_open_ioctl_locked, after taking the gt->perf.lock mutex for serializing with any non-file-operation driver hooks 🔥

---

⭐ RETURN ⭐

you get either a newly opened i915 Perf stream file descriptor, or a negative error code on failure. slay or cry, there is no in between 💀

---

🌈 SEE ALSO 🌈

okay this list is long, so buckle up 🧚 — but every single one of these matters:

• Kernel file ./drivers/gpu/drm/i915/i915_perf.c
• i915 Perf Overview(9)
• i915 Perf History and Comparison with Core Perf(9)
• OA Tail Pointer Race(9)
• struct perf_open_properties(9)
• oa_buffer_check_unlocked(9)
• append_oa_status(9)
• append_oa_sample(9)
• gen8_append_oa_reports(9)
• gen8_oa_read(9)
• gen7_append_oa_reports(9)
• gen7_oa_read(9)
• i915_oa_wait_unlocked(9)
• i915_oa_poll_wait(9)
• i915_oa_read(9)
• oa_get_render_ctx_id(9)
• oa_put_render_ctx_id(9)
• i915_oa_stream_enable(9)
• i915_oa_stream_disable(9)
• i915_oa_stream_init(9)
• i915_perf_read(9)
• i915_perf_poll_locked(9)
• i915_perf_poll(9)
• i915_perf_enable_locked(9)
• i915_perf_disable_locked(9)
• i915_perf_ioctl_locked(9)
• i915_perf_ioctl(9)
• i915_perf_destroy_locked(9)
• i915_perf_release(9)
• i915_perf_open_ioctl_locked(9)
• read_properties_unlocked(9)
• i915_perf_register(9)
• i915_perf_unregister(9)
• i915_perf_add_config_ioctl(9)
• i915_perf_remove_config_ioctl(9)
• i915_perf_init(9)
• i915_perf_fini(9)
• i915_perf_ioctl_version(9)

---

🥺 and that's the page!! sourced from ./drivers/gpu/drm/i915, dated October 2026, and yes it really is i915_perf_open_ioctl(9) the whole way through. read it, bookmark it, tell your friends. mwah 💋💜