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authorBjörn Töpel <bjorn.topel@intel.com>2018-06-04 14:57:13 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2018-06-04 18:21:02 +0300
commitbbff2f321a864ee07c9d3d1245af498023146951 (patch)
tree962414a03f749ce22e52ed553780a74216992d0a /include/uapi/linux/if_xdp.h
parenta509a95536a86ef84deb16c656d741437791b414 (diff)
downloadlinux-bbff2f321a864ee07c9d3d1245af498023146951.tar.xz
xsk: new descriptor addressing scheme
Currently, AF_XDP only supports a fixed frame-size memory scheme where each frame is referenced via an index (idx). A user passes the frame index to the kernel, and the kernel acts upon the data. Some NICs, however, do not have a fixed frame-size model, instead they have a model where a memory window is passed to the hardware and multiple frames are filled into that window (referred to as the "type-writer" model). By changing the descriptor format from the current frame index addressing scheme, AF_XDP can in the future be extended to support these kinds of NICs. In the index-based model, an idx refers to a frame of size frame_size. Addressing a frame in the UMEM is done by offseting the UMEM starting address by a global offset, idx * frame_size + offset. Communicating via the fill- and completion-rings are done by means of idx. In this commit, the idx is removed in favor of an address (addr), which is a relative address ranging over the UMEM. To convert an idx-based address to the new addr is simply: addr = idx * frame_size + offset. We also stop referring to the UMEM "frame" as a frame. Instead it is simply called a chunk. To transfer ownership of a chunk to the kernel, the addr of the chunk is passed in the fill-ring. Note, that the kernel will mask addr to make it chunk aligned, so there is no need for userspace to do that. E.g., for a chunk size of 2k, passing an addr of 2048, 2050 or 3000 to the fill-ring will refer to the same chunk. On the completion-ring, the addr will match that of the Tx descriptor, passed to the kernel. Changing the descriptor format to use chunks/addr will allow for future changes to move to a type-writer based model, where multiple frames can reside in one chunk. In this model passing one single chunk into the fill-ring, would potentially result in multiple Rx descriptors. This commit changes the uapi of AF_XDP sockets, and updates the documentation. Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'include/uapi/linux/if_xdp.h')
-rw-r--r--include/uapi/linux/if_xdp.h12
1 files changed, 5 insertions, 7 deletions
diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
index 4737cfe222f5..e411d6f9ac65 100644
--- a/include/uapi/linux/if_xdp.h
+++ b/include/uapi/linux/if_xdp.h
@@ -48,8 +48,8 @@ struct xdp_mmap_offsets {
struct xdp_umem_reg {
__u64 addr; /* Start of packet data area */
__u64 len; /* Length of packet data area */
- __u32 frame_size; /* Frame size */
- __u32 frame_headroom; /* Frame head room */
+ __u32 chunk_size;
+ __u32 headroom;
};
struct xdp_statistics {
@@ -66,13 +66,11 @@ struct xdp_statistics {
/* Rx/Tx descriptor */
struct xdp_desc {
- __u32 idx;
+ __u64 addr;
__u32 len;
- __u16 offset;
- __u8 flags;
- __u8 padding[5];
+ __u32 options;
};
-/* UMEM descriptor is __u32 */
+/* UMEM descriptor is __u64 */
#endif /* _LINUX_IF_XDP_H */