From nobody Fri Mar 04 20:56:42 2022 X-Original-To: bugs@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 543C419FEF04 for ; Fri, 4 Mar 2022 20:56:43 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4K9KsR1FYRz3Kq5 for ; Fri, 4 Mar 2022 20:56:43 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id F19FA134FD for ; Fri, 4 Mar 2022 20:56:42 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 224KugaD041963 for ; Fri, 4 Mar 2022 20:56:42 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 224KuggZ041962 for bugs@FreeBSD.org; Fri, 4 Mar 2022 20:56:42 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 262316] em(4) does not autonegotiate when fixed media is set Date: Fri, 04 Mar 2022 20:56:42 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: se@FreeBSD.org X-Bugzilla-Status: Open X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated List-Id: Bug reports List-Archive: https://lists.freebsd.org/archives/freebsd-bugs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-bugs@freebsd.org MIME-Version: 1.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1646427403; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M9gErxZyxUdGZZUlEmSlzrqHOzQ78FcVnEVuIXGkYrQ=; b=yjR6HRbtNxC285847aKnNxnZnZjU0bFhKVGu+Uxxk2FjQ7eIRZS6MIGH/Md1RnVfe5HNdp 8Qy9v112iE/vzPSDBuIu0VWLVKUxAZEOydGnku/8OMttVo5iAzr+JpwX0yDbYds9/ShSyR AOAOQBcDu+EBGNgSSIdX1e5mWkzd3pKXrhR8HYRd+rqHAZWuabXoLRpfbNjyx9i07koLV+ /J5E7/e1e4jXxLR+rSefhGx0Bgd63RwsVNDD7Z0fCVKKITSjWpBK44dUuZgA0UklDtMq+V dd3UmkPtRugI1FUbJd7HUwpmZHFJ2I/wRAdD4RZx7ryl+VZd5FfbRu+s1Dnpsw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1646427403; a=rsa-sha256; cv=none; b=BrvLahUjNGt1g5sP3bbML+CTZYNra8R113aeUyEIB17a7j0442A6yGA9owfQKGg4RUjTnQ 3guCcTWPP5UQRMK1tVomDvg8E3PIFodjvXVHfAYNm6Cv8qjqZ5dXOfEie8lJ1wa3MJcL8H L4v7zJtxtBVo5iVw1zjz3EBQPUWVUMMcZpgpHNbmu9VSqa8k0SZSt5caTXa6OxygZPhwuA y2P8LGRin1MZIggsEl2LaA6jRRIiXrMSKTU/fIES0/eNVNHdUwP9SVblOadYnVKGcsZObw oxjq/FLLyrQX4AzlZkmplrNMVioYYWTdUkHaIFD6q0rzaNfXLKoumX0UQHFuDg== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D262316 --- Comment #4 from Stefan E=C3=9Fer --- (In reply to J.R. Oldroyd from comment #2) Quoting the Duplex_mismatch article: ------------------------------------------------------------------- Duplex mismatch due to autonegotiation When a device set to autonegotiation is connected to a device that is not u= sing autonegotiation, the autonegotiation process fails. The autonegotiating end= of the connection is still able to correctly detect the speed of the other end, but cannot correctly detect the duplex mode. For backward compatibility with Ethernet hubs, the standard requires the autonegotiating device to use half duplex in these conditions. Therefore, the autonegotiating end of the connection uses half duplex while the non-negotiating peer is locked at full duplex, and this is a duplex mismatch. ------------------------------------------------------------------- I do not have access to a current version of the standard (802.3-2018), but when I last worked on an Ethernet driver the standard required a device to either participate in auto-negotiation or to be manually configured. In the latter case it does not respond to the auto-negotiation bursts from the oth= er device, and therefore there is no mechanism that could let the other device detect wether the manually configured device is set to half-duplex or full-duplex. The standard does therefore require the device set to perform the auto-negotiation to select half-duplex mode. This mode offers less performa= nce than full-duplex on both ends, but prevents an extreme amount of collisions= to impact the network at large. There are not any hubs left, today, but AFAIK the above cited text is still part of the standard. A manually configured Ethernet device must ignore the auto-negotiation requ= est. And half-duplex has been specified as the safe default mode. Use auto-negotiation on all interfaces. It has been specified more than 20 years ago, and if really should not work correctly, then manually configure *all* affected interfaces. I'm not going to close the PR again at this time - but I'll oppose any comm= it that violates the Ethernet standard. Please cite the IEEE-802.3 clause that changed the previously specified behavior in case of one auto-negotiating and one manually configured device= , if this has actually been changed in a later version of the standard than I had access to. --=20 You are receiving this mail because: You are the assignee for the bug.=