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authorMichael Chan <michael.chan@broadcom.com>2017-12-16 11:09:40 +0300
committerDavid S. Miller <davem@davemloft.net>2017-12-19 18:38:36 +0300
commitfb1f5f79ae96331a0201b4080d34f3bc3b5c0b1d (patch)
treecf5acb01f5d79f0f140b0b100d3ba46bef881fed /Documentation/networking
parent398b841e4ad69a822f615442b5ea4ca767330a3b (diff)
downloadlinux-fb1f5f79ae96331a0201b4080d34f3bc3b5c0b1d.tar.xz
net: Introduce NETIF_F_GRO_HW.
Introduce NETIF_F_GRO_HW feature flag for NICs that support hardware GRO. With this flag, we can now independently turn on or off hardware GRO when GRO is on. Previously, drivers were using NETIF_F_GRO to control hardware GRO and so it cannot be independently turned on or off without affecting GRO. Hardware GRO (just like GRO) guarantees that packets can be re-segmented by TSO/GSO to reconstruct the original packet stream. Logically, GRO_HW should depend on GRO since it a subset, but we will let individual drivers enforce this dependency as they see fit. Since NETIF_F_GRO is not propagated between upper and lower devices, NETIF_F_GRO_HW should follow suit since it is a subset of GRO. In other words, a lower device can independent have GRO/GRO_HW enabled or disabled and no feature propagation is required. This will preserve the current GRO behavior. This can be changed later if we decide to propagate GRO/ GRO_HW/RXCSUM from upper to lower devices. Cc: Ariel Elior <Ariel.Elior@cavium.com> Cc: everest-linux-l2@cavium.com Signed-off-by: Michael Chan <michael.chan@broadcom.com> Acked-by: Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/netdev-features.txt9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/networking/netdev-features.txt b/Documentation/networking/netdev-features.txt
index 7413eb05223b..c77f9d57eb91 100644
--- a/Documentation/networking/netdev-features.txt
+++ b/Documentation/networking/netdev-features.txt
@@ -163,3 +163,12 @@ This requests that the NIC receive all possible frames, including errored
frames (such as bad FCS, etc). This can be helpful when sniffing a link with
bad packets on it. Some NICs may receive more packets if also put into normal
PROMISC mode.
+
+* rx-gro-hw
+
+This requests that the NIC enables Hardware GRO (generic receive offload).
+Hardware GRO is basically the exact reverse of TSO, and is generally
+stricter than Hardware LRO. A packet stream merged by Hardware GRO must
+be re-segmentable by GSO or TSO back to the exact original packet stream.
+Hardware GRO is dependent on RXCSUM since every packet successfully merged
+by hardware must also have the checksum verified by hardware.