Customize MGBE / 25G QSFP

Overview

Thor T264 exposes mgbe0..mgbe3. On a custom carrier, the 25G QSFP cage (or 10G / 1G fiber path) is wired to one of them through SerDes — with or without an external MDIO PHY in front of the cage. This skill renders the kernel-DT overlay that pairs the BPMP allocation with kernel-side status="okay" + PHY plumbing on &mgbeN.

Out of scope:

• UPHY lane allocation — owned by /jetson-customize-uphy. Refuse if the chosen uphy1-config-N doesn't allocate the target MGBE.
• All ODMDATA tokens (mgbeN-speed-*, sub-node mgbeN_status=*) — owned by /jetson-customize-uphy in its single atomic ODMDATA commit. This skill MUST NOT touch ODMDATA=.