Date: Fri, 17 Oct 2014 21:42:06 +0000 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 Message-ID: <bug-194314-2472-dqaNXc0QkO@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-194314-2472@https.bugs.freebsd.org/bugzilla/> References: <bug-194314-2472@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194314 --- Comment #10 from Garrett Cooper <ngie@FreeBSD.org> --- (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? -- You are receiving this mail because: You are the assignee for the bug.
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