cxl_switch_gather_bandwidth(9)

✨ cxl_switch_gather_bandwidth(9) ✨

okay bestie, welcome to the kernel API manual 💅 this one's a <blue>9</blue>-section page (kernel internals, iykyk), and it's all about hoarding bandwidth at the switch level 🎀

---

🌸 NAME 🌸

cxl_switch_gather_bandwidth — literally collect all the bandwidth at switch level, in an xarray, no cap 🫶

---

🦋 SYNOPSIS 🦋

struct xarray * cxl_switch_gather_bandwidth (struct cxl_region *cxlr ,
struct xarray *input_xa , bool *gp_is_root );

---

🎀 ARGUMENTS 🎀

• cxlr — the region being operated on, the main character of this whole function ✨
• input_xa — xarray indexed by the upstream device of a switch, holding data of struct cxl_perf_ctx 💖
• gp_is_root — (output) a bool telling you whether the grandparent is cxl root. yes she's an output param, she writes back 👑

---

🌈 RETURN 🌈

an xarray of resulting cxl_perf_ctx per parent switch or root port — or ERR_PTR(-errno) if things go sideways 😭

---

💜 DESCRIPTION 💜

So here's the vibe: we iterate through the xarray 🔥

Then we take the minimum of these three besties:

• the downstream calculated bandwidth
• the upstream link bandwidth
• the SSLBIS of the upstream switch, if it exists (conditional queen 🙈)

Then we sum the resulting bandwidth under the switch upstream device or an RP device ✨

And she's reusable, fr fr — the function can be iterated over multiple switches if the switches are present, periodt 💅

---

🍓 SEE ALSO 🍓

• Kernel file ./drivers/cxl/core/cdat.c
• cxl_coordinates_combine(9)
• cxl_endpoint_gather_bandwidth(9)
• cxl_rp_gather_bandwidth(9)
• cxl_hb_gather_bandwidth(9)
• cxl_region_update_bandwidth(9)
• cxl_region_shared_upstream_bandwidth_update(9)

go read those too, they're iconic, iykyk 👑

---

and that's the page, bestie!! 🧚 this little gem lives in ./drivers/cxl/core and the version/date vibe is October 2026 — see you next time, mwah 💖🦋🌸