Date: Fri, 26 Sep 2025 09:45:06 +0200 From: Michael Tuexen <michael.tuexen@lurchi.franken.de> To: John Nielsen <lists@jnielsen.net> Cc: net@freebsd.org, virtualization@freebsd.org, np@freebsd.org Subject: Re: Chelsio (cxgbe) VF on FreeBSD guest under KVM requires -rxcsum Message-ID: <CF7D677F-2D3A-41B5-A3F1-0FCA844D206F@lurchi.franken.de> In-Reply-To: <5D2A2499-4B43-4FE6-AA5A-AD334BC4E872@jnielsen.net> References: <5D2A2499-4B43-4FE6-AA5A-AD334BC4E872@jnielsen.net>
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> On 26. Sep 2025, at 02:58, John Nielsen <lists@jnielsen.net> wrote: >=20 > Hi- >=20 > Not sure if this is a known issue or even an issue on the FreeBSD side = but decided to ask here first. I=E2=80=99m happy to put in a bug report = if appropriate. >=20 > I have a hypervisor machine running Arch Linux with KVM, Qemu and = libvirtd. The machine has a Chelsio T520-CR adapter. I recently began = passing through virtual functions of the NIC to several of the guests I = run on the hypervisor. One of the guests runs Windows 11, and the change = was seamless. Two of the guests are running FreeBSD (14.3 or so). On = each of them the VFs were readily identified and configured (using DHCP = in one case), and ping and ARP appeared to work fine. However, TCP and = UDP traffic to the guests never received a response. After some = head-scratching and troubleshooting I discovered that running = =E2=80=9Cifconfig cxlv0 -rxcsum=E2=80=9D immediately allowed traffic to = flow as expected. Hi John, I don't have access to such a network card. Just to be clear: you are = running the =E2=80=9Cifconfig cxlv0 -rxcsum=E2=80=9D command inside the = guest running FreeBSD, right? What is the peer, when you mention TCP and UDP do not work? Is it the = host running Linux? Is it another VM? Is it some external host? >=20 > As workarounds go that isn=E2=80=99t terrible, but I was surprised = that the FreeBSD guests required this adjustment while the Windows one = did not. >=20 > As a point of reference I have another hypervisor machine that runs = FreeBSD 14-STABLE. It also has a=20 So the host runs FreeBSD and you use bhyve to run some VM? > Chelsio T520-CR adapter. FreeBSD guests on that machine do not require = =E2=80=9C-rxcsum=E2=80=9D in order to use the Chelsio virtual functions. The guests run FreeBSD-STABLE or Freebsd 14.3? What is the peer, when you mention TCP and UDP do not work? Is it the = host running Linux? Is it another VM? Is it some external host? >=20 > Let me know if anyone can shed some light on this. I=E2=80=99m happy = to provide additional details or run further tests if needed. Thank you! Maybe I can, but I need to understand the scenario... Best regards Michael >=20 > -John >=20 >=20
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