From owner-freebsd-net@FreeBSD.ORG Mon Oct 20 18:13:38 2014 Return-Path: Delivered-To: freebsd-net@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id B1AC21E4 for ; Mon, 20 Oct 2014 18:13:38 +0000 (UTC) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 9881133C for ; Mon, 20 Oct 2014 18:13:38 +0000 (UTC) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.14.9/8.14.9) with ESMTP id s9KIDcj0017956 for ; Mon, 20 Oct 2014 18:13:38 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-net@FreeBSD.org Subject: [Bug 194314] [ixgbe] driver makes some dangerous assumptions with struct mbuf sizing with IXGBE_RX_COPY_LEN Date: Mon, 20 Oct 2014 18:13:38 +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: 11.0-CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: ricera10@gmail.com X-Bugzilla-Status: Needs Triage X-Bugzilla-Priority: Normal X-Bugzilla-Assigned-To: freebsd-net@FreeBSD.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Oct 2014 18:13:38 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194314 --- Comment #12 from Eric Joyner --- (In reply to Garrett Cooper from comment #10) > (In reply to Eric Joyner from comment #8) > > So it sounds like we may just need to change IXGBE_RX_COPY_LEN from a fixed > > value of 160 to something that's calculated based on the length of struct > > m_hdr and struct m_pkthdr combined. > > > > I think they got 160 by adding together the size of the two header structs > > (88 in FreeBSD amd64), adding some number (8) to make that size divisible by > > 32 (96 % 32 == 0), and then subtracted that from MSIZE (256) to get > > IXGBE_RX_COPY_LEN (160), while keeping the padding added as > > IXGBE_RX_COPY_ALIGN. > > A couple questions then: > > - What architectures is this driver supported on? > - Is this optimization only valid for amd64? > - Why 32? - At least i386 and amd64, but it should theoretically work on anything with a PCI-E slot - This optimization specifically was contributed by scottl/luigi, looking at the commit logs. You should ask either of those two for details. - Doesn't the comment in the code you posted answer that? -- You are receiving this mail because: You are the assignee for the bug.