On 2014/12/3 22:51, Richardson, Bruce wrote: > On Wed, Dec 03, 2014 at 01:59:58PM +0000, Qiu, Michael wrote: >> On 2014/12/3 19:43, Richardson, Bruce wrote: >>> On Wed, Dec 03, 2014 at 07:28:19PM +0800, Michael Qiu wrote: >>>> app/test-pmd/csumonly.c: In function ?get_psd_sum?: >>>> build/include/rte_ip.h:161: error: dereferencing pointer ?u16? >>>> does break strict-aliasing rules >>>> build/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 *'. >>>> >>> What compiler version is this with? Is there any other way to fix this >>> other than disabling the compiler warnings. Turning off strict aliasing may >>> affect performance as it reduces the number of optimizations that the >>> compiler >>> can perform. >> The compile version is: >> >> $ gcc -v >> Using built-in specs. >> Target: x86_64-redhat-linux >> ... >> gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC) >> >> >> The OS is centos6.5 x86_64 >> >> >> Actually, another possible solution is, as gcc manual shows, use union. >> In function rte_raw_cksum() of lib/librte_net/rte_ip.h: >> >> static inline uint16_t >> rte_raw_cksum(const char *buf, size_t len){ >> union { >> const char *ubuf; >> const uint16_t *uu16; >> } convert; >> >> convert.ubuf = buf; >> const uint16_t *u16 = convert.uu16; >> ... >> } >> >> This may be work, but not test yet. >> >> Any comments about this solution? > what happens if you make rte_raw_cksum take a void * (or const void *) > parameter > instead of "const char *"?
"size_t len" is for type char, it is the the array size(for char array is byte numbers), if we use void *, the meaning maybe confuse I think. But it should work with other code change. Thanks, Michael > > /Bruce >