Re: [Libvir] [PATCH] to run on IA64

Hi, Mark Thank you for your suggestion. I just compiled it sucessfuly. It should be work. I will do test it tomorrow. Thanks Atsushi　SAKAI Mark McLoughlin <markmc(a)redhat.com&gt; wrote: > Hi, > Thanks for that ... > > On Tue, 2007-02-20 at 13:51 +0900, Atsushi SAKAI wrote: > > > > > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_family = AF_INET; > > > > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr = inaddr; > > > > + ((struct sockaddr_in *)((void *)&ifr.ifr_addr))->sin_family = AF_INET; > > > > + ((struct sockaddr_in *)((void *)&ifr.ifr_addr))->sin_addr = inaddr; > > > bridge.c: In function 'brSetInetAddr': > > bridge.c:344: warning: cast increases required alignment of target type > > bridge.c:345: warning: cast increases required alignment of target type > > bridge.c: In function 'brGetInetAddr': > > bridge.c:381: warning: cast increases required alignment of target type > > Okay, my understanding of this is that: > > - The warning is caused by -Wcast-align > > - Our problem is that we're casting between pointers to struct > sockaddr and struct sockaddr_in, which look like > > struct sockaddr > { > unsigned short int sa_family; > }; > > struct sockaddr_in > { > unsigned short int sin_family; > uint16_t sin_port; > struct { uint32_t s_addr } sin_addr; > }; > > - Because of the uint32_t, struct sockaddr_in is required to be > aligned to a 4 byte boundary, whereas on ia64 struct sockaddr is > only required to be aligned to a 2 byte boundary > > - If we look at in the context of struct ifreq, though: > > struct ifreq > { > .... > union { > struct sockaddr ifru_addr; > .... > void *ifru_data; > } ifr_ifru; > }; > #define ifr_addr ifr_ifru.ifru_addr > #define ifr_data ifr_ifru.ifru_data > > we see that because of the void pointer in the union, the struct > sockaddr is actually guaranteed to be aligned to 8 bytes and so the > warning can be ignored. > > - I'd prefer to avoid the void pointer cast as someone could come > along and wonder whether the cast is hiding a genuine problem. > > - So, I think I'll go ahead and do it this way instead: > > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_family = AF_INET; > - ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr = inaddr; > + ((struct sockaddr_in *)&ifr.ifr_data)->sin_family = AF_INET; > + ((struct sockaddr_in *)&ifr.ifr_data)->sin_addr = inaddr; > > Cheers, > Mark. > -- Libvir-list mailing list Libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list