From 2b039d5f20a34016ecaf9b26f8f8b6c4a81bf4b6 Mon Sep 17 00:00:00 2001 From: Michael Qiu Date: Thu, 4 Dec 2014 12:16:04 +0800 Subject: [PATCH] net: fix build with gcc 4.4.7 and strict aliasing MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit include/rte_ip.h:161: error: dereferencing pointer ‘u16’ does break strict-aliasing rules include/rte_ip.h:157: note: initialized from here ... The root cause is that, compile enable strict aliasing by default, while in function rte_raw_cksum() try to convert 'const char *' to 'const uint16_t *'. This workaround is to solve the compile issue of GCC strict-aliasing (two different type pointers should not be point to the same memory address). For GCC 4.4.7 it will definitely occurs if flags "-fstrict-aliasing" and "-Wall" used. Signed-off-by: Michael Qiu [Thomas: add workaround comment] Acked-by: Thomas Monjalon --- lib/librte_net/rte_ip.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h index 61e44579a3..46f049716a 100644 --- a/lib/librte_net/rte_ip.h +++ b/lib/librte_net/rte_ip.h @@ -154,7 +154,9 @@ struct ipv4_hdr { static inline uint16_t rte_raw_cksum(const char *buf, size_t len) { - const uint16_t *u16 = (const uint16_t *)buf; + /* workaround gcc strict-aliasing warning */ + uintptr_t ptr = (uintptr_t)buf; + const uint16_t *u16 = (const uint16_t *)ptr; uint32_t sum = 0; while (len >= (sizeof(*u16) * 4)) { -- 2.20.1