NetBSD Problem Report #60038

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Date: Wed, 25 Feb 2026 11:54:57 +0000 (UTC)
From: stranche@free.fr
Reply-To: stranche@free.fr
To: gnats-bugs@NetBSD.org
Subject: Thinkpad X270 with Ethernet on USBC ifconfig reports wrong speed
X-Send-Pr-Version: www-1.0
X-From4GNATS: "stranche@free.fr via gnats" <gnats-admin@NetBSD.org>

>Number:         60038
>Category:       kern
>Synopsis:       Thinkpad X270 with Ethernet on USBC ifconfig reports wrong speed
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    gutteridge
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Feb 25 11:55:02 +0000 2026
>Last-Modified:  Thu Feb 26 13:45:00 +0000 2026
>Originator:     Stephane Tranchemer
>Release:        10.1
>Organization:
-
>Environment:
NetBSD lenonetbsd.mydomain 10.1 NetBSD 10.1 (GENERIC) #0: Mon Dec 16 13:08:11 UTC 2024  mkrepro@mkrepro.NetBSD.org:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
Seen on a Lenovo Thinkpad X270 with Ethernet adapter on USBC.

NetBSD 10.1

dmesg output is correct with a 1000Mbps link:

> $ dmesg | grep ure0
> [     3.055330] ure0 at uhub2 port 4
> [     3.085326] ure0: Realtek (0x0bda) USB 10/100/1000 LAN (0x8153), rev 3.20/31.fd, addr 3
> [     3.115327] ure0: RTL8153 unknown ver 6010
> [     3.215326] rgephy0 at ure0 phy 0: RTL8251 1000BASE-T media interface, rev. 0
> [     3.275326] ure0: Ethernet address 00:e0:de:ad:be:ef

ifconfig reports wrong speed, 100Mbps instead of Gigabit.

> $ ifconfig ure0
> ure0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> capabilities=0x2aa00<IP4CSUM_Tx,TCP4CSUM_Tx,UDP4CSUM_Tx,TCP6CSUM_Tx>
>         capabilities=0x2aa00<UDP6CSUM_Tx>
>         enabled=0
>         ec_capabilities=0x1<VLAN_MTU>
>         ec_enabled=0
>         address: 00:e0:de:ad:be:ef
>         media: Ethernet autoselect (100baseTX full-duplex)
>         status: active
>         inet6 fe80::aa8a:49e:dead:beef%ure0/64 flags 0 scopeid 0x2
>         inet6 2405:de:ad:be:ef::10/64 flags 0x40<AUTOCONF>
>         inet 192.168.54.215/24 broadcast 192.168.54.255 flags 0

An iperf with another machine on the LAN shows speed definitely beyond a 100Mbps link

> $ iperf -s
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size:  128 KByte (default)
> ------------------------------------------------------------
> [  1] local 192.168.54.10 port 5001 connected with 192.168.54.215 port 65535
> [ ID] Interval       Transfer     Bandwidth
> [  1] 0.00-10.05 sec  55.5 MBytes  46.3 Mbits/sec


>How-To-Repeat:
Link a USB-C ethernet adapter on the machine
>Fix:
unknown

>Release-Note:

>Audit-Trail:
From: stephane Tranchemer <stranche@free.fr>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Wed, 25 Feb 2026 22:55:39 +0900

 Oh no, I made a mistake in my report... silly me.

 The iperf showed a speed of 46.3 Mbits/sec, not MBytes.

 Confirmed doing some file transfers, speed caps a something like 5MBytes/s.
 Using a different machine running Windows (yeah I know, don't shout) shows speeds more on par with Gigabit link.

 So actually USB-C Ethernet speed is capped, at least on NetBSD 10.1?


From: "Jonathan A. Kollasch" <jakllsch@kollasch.net>
To: gnats-bugs@netbsd.org
Cc: misc-bug-people@netbsd.org, gnats-admin@netbsd.org,
	netbsd-bugs@netbsd.org
Subject: Re: misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Wed, 25 Feb 2026 08:09:39 -0600

 > [     3.115327] ure0: RTL8153 unknown ver 6010

 This is likely the source of the issue: the driver doesn't (yet) fully
 support your USB to Ethernet adapter.

From: stephane Tranchemer <stranche@free.fr>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Wed, 25 Feb 2026 23:25:59 +0900

 Oh, RTL8153 driver was introduced with NetBSD 9.0, so either incomplete 
 or some revision occurred...

From: stephane Tranchemer <stranche@free.fr>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Wed, 25 Feb 2026 23:34:54 +0900

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 That "ver 6010" thing seems to point to in fact the RTL8153B... talk 
 about creating confusion.

 Confirmed with the introduction of this patch in the Linux kernel 4.13: 
 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/net/usb/r8152.c?h=v4.13&id=65b82d696b9e84fda6dd7df61801b57d3e7fb976

 Hope it can reach someone that can actually use that info.

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     <p>That "<span style="white-space: pre-wrap">ver 6010" thing seems to point to in fact the RTL8153B... talk about creating confusion.</span></p>
     <p><span style="white-space: pre-wrap">Confirmed with the introduction of this patch in the Linux kernel 4.13:
 <a class="moz-txt-link-freetext" href="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/net/usb/r8152.c?h=v4.13&amp;id=65b82d696b9e84fda6dd7df61801b57d3e7fb976">https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/net/usb/r8152.c?h=v4.13&amp;id=65b82d696b9e84fda6dd7df61801b57d3e7fb976</a></span></p>
     <p><span style="white-space: pre-wrap">Hope it can reach someone that can actually use that info.</span></p>
   </body>
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From: "David H. Gutteridge" <david@gutteridge.ca>
To: Gnats Bugs <gnats-bugs@netbsd.org>
Cc: 
Subject: Re: misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Wed, 25 Feb 2026 12:27:30 -0500

 On Wed, 25 Feb 2026 at 08:09:39 -0600, Jonathan A. Kollasch wrote:
 >> [     3.115327] ure0: RTL8153 unknown ver 6010

 > This is likely the source of the issue: the driver doesn't (yet) fully
 > support your USB to Ethernet adapter.

 It's true that this chip revision has some differences, from looking at
 the OpenBSD driver. (This was already something I was examining,
 bringing support for this exact variant over to our code.)

 Though, here's my example of the same (well, almost):

 [     1.696515] ure0 at uhub0 port 1
 [     1.696515] ure0: Realtek (0x0bda) USB 10/100/1000 LAN (0x8153), rev 
 3.00/31.00, addr 1
 [     1.696515] ure0: RTL8153 unknown ver 6010
 [     1.756517] rgephy2 at ure0 phy 0: RTL8251 1000BASE-T media 
 interface, rev. 0

 ure0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
 	capabilities=0x2aa00<IP4CSUM_Tx,TCP4CSUM_Tx,UDP4CSUM_Tx,TCP6CSUM_Tx>
 	capabilities=0x2aa00<UDP6CSUM_Tx>
 	enabled=0
 	ec_capabilities=0x1<VLAN_MTU>
 	ec_enabled=0
 	address: f2:00:8e:82:c2:c6
 	media: Ethernet autoselect (1000baseT full-duplex)
 	status: active

 It does set/support gigabit for me, which suggests there could be
 something else at play with NetBSD as well.

 Regards,

 Dave

Responsible-Changed-From-To: misc-bug-people->gutteridge
Responsible-Changed-By: gutteridge@NetBSD.org
Responsible-Changed-When: Wed, 25 Feb 2026 22:49:32 +0000
Responsible-Changed-Why:
I will see if I can help with this. (Also, refile this under "kern" while here.)

From: "David H. Gutteridge" <david@gutteridge.ca>
To: Gnats Bugs <gnats-bugs@netbsd.org>
Cc: 
Subject: Re: misc/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Wed, 25 Feb 2026 20:26:50 -0500

 I replied in haste earlier, I should have added that this example:

 ure0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
      capabilities=0x2aa00<IP4CSUM_Tx,TCP4CSUM_Tx,UDP4CSUM_Tx,TCP6CSUM_Tx>
      capabilities=0x2aa00<UDP6CSUM_Tx>
      enabled=0
      ec_capabilities=0x1<VLAN_MTU>
      ec_enabled=0
      address: f2:00:8e:82:c2:c6
      media: Ethernet autoselect (1000baseT full-duplex)
      status: active

 ... is from NetBSD 11.99.5 (on aarch64), running on a NanoPi R2S, where
 this device is permanently attached to the USB bus, not via USB-C.

 It might be worth trying a more recent kernel to see what happens.

 Regards,

 Dave

From: stephane Tranchemer <stranche@free.fr>
To: gnats-bugs@netbsd.org, gutteridge@netbsd.org, gnats-admin@netbsd.org,
 netbsd-bugs@netbsd.org
Cc: 
Subject: Re: kern/60038: Thinkpad X270 with Ethernet on USBC ifconfig reports
 wrong speed
Date: Thu, 26 Feb 2026 22:43:44 +0900

 Tried to run NetBSD 11.0-RC1 to see, same result.

>Unformatted:

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