[dpdk-dev] [PATCH] net/af_xdp: fix 32-bit build for older kernels

[Ciara Loftus]

'uint64_t' is used to hold pointers in multiple locations in the
copy-mode code (used for kernels before 5.4). For a 32-bit build
this assumption is wrong and results in build errors. This commit
replaces such instances of 'uint64_t' with 'uintptr_t'.

While the copy-mode code will now compile for 32-bit, the PMD is
not expected to work and will fail at initialisation due to some
limitations in the kernel that were subsequently removed in v5.4.
Add a note to the docs to flag this limitation.

Fixes: f1debd77efaf ("net/af_xdp: introduce AF_XDP PMD")
Fixes: d8a210774e1d ("net/af_xdp: support unaligned umem chunks")
Cc: sta...@dpdk.org

Signed-off-by: Ciara Loftus <ciara.lof...@intel.com>
---
 doc/guides/nics/af_xdp.rst          | 1 +
 drivers/net/af_xdp/rte_eth_af_xdp.c | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
index 052e59a3ae..5ed24374f8 100644
--- a/doc/guides/nics/af_xdp.rst
+++ b/doc/guides/nics/af_xdp.rst
@@ -50,6 +50,7 @@ This is a Linux-specific PMD, thus the following 
prerequisites apply:
 *  For PMD zero copy, it requires kernel version later than v5.4-rc1;
 *  For shared_umem, it requires kernel version v5.10 or later and libbpf 
version
    v0.2.0 or later.
+*  For 32-bit OS, a kernel with version 5.4 or later is required.
 
 Set up an af_xdp interface
 -----------------------------
diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c 
b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 4076ff797c..75ff1c00b2 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -349,7 +349,7 @@ af_xdp_rx_cp(void *queue, struct rte_mbuf **bufs, uint16_t 
nb_pkts)
 
        for (i = 0; i < rcvd; i++) {
                const struct xdp_desc *desc;
-               uint64_t addr;
+               uintptr_t addr;
                uint32_t len;
                void *pkt;
 
@@ -402,7 +402,7 @@ pull_umem_cq(struct xsk_umem_info *umem, int size, struct 
xsk_ring_cons *cq)
        n = xsk_ring_cons__peek(cq, size, &idx_cq);
 
        for (i = 0; i < n; i++) {
-               uint64_t addr;
+               uintptr_t addr;
                addr = *xsk_ring_cons__comp_addr(cq, idx_cq++);
 #if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG)
                addr = xsk_umem__extract_addr(addr);
@@ -1005,7 +1005,7 @@ xsk_umem_info *xdp_umem_configure(struct pmd_internals 
*internals,
        char ring_name[RTE_RING_NAMESIZE];
        char mz_name[RTE_MEMZONE_NAMESIZE];
        int ret;
-       uint64_t i;
+       uintptr_t i;
 
        umem = rte_zmalloc_socket("umem", sizeof(*umem), 0, rte_socket_id());
        if (umem == NULL) {
-- 
2.17.1