RealTek r8157 not properly detected by kernel. Uses cdc_ncm module instead
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Description
OS: Oracle Linux 10
Kernel: 6.12.0-200.74.27.el10uek.x86_64
Problem:
It appears either the kernel supplied r8152 module does not properly identify the r8157 device OR it does not support the device. This causes the network device to run at half duplex and auto negotiation to be off.
FIX:
The fix is to blacklist the cdc_ncm module and make/install the module from RealTek. This restores full operation to the network device, at full duplex, with auto negotiation on. All speeds are advertised.
INFORMATION after installation of Realtek module:
Realtek module version:
version: v2.21.4 (2025/10/28)
license: GPL
description: Realtek RTL8152/RTL8153 Based USB Ethernet Adapters
From lsusb:
Bus 004 Device 002: ID 0bda:8157 Realtek Semiconductor Corp. 5G Ethernet Adapter
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by examining the kernel's r8152 and cdc_ncm handling for USB device ID 0bda:8157 on the reported Oracle Linux 10 kernel. Reproduce the detection and link negotiation behavior, then verify that the device uses the appropriate driver with full duplex, auto-negotiation, and advertised speeds without relying on the Realtek out-of-tree module or a blacklist.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- linux
- Domain
- networking, operating-systems
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 45/100