On Tue, Nov 03, 2009 at 06:01:46PM +0100, Jan Engelhardt wrote: > > > >If GCC can see at the inlining point that 'ptr' is of a type that > >should be properly aligned it can inline the memcpy and still emit > >the very unaligned load or store that you're trying to avoid. > > Hi Dave, > > Indeed it seems to be this way. Hm, bad. > > What codes are you using on your alignment-sensitive SPARCs - > the standard bitshifting, "char *p; p[0]<<24 | p[1]<<16 | p[2]<<8 | p[3]"? Hi all, I am not very familiar with these kind of problems (alignment). If I understand correctly, what I need to avoid is playing with pointers on a buffer, especially if trying to read a structure. Since what I am trying to read is formatted as following: marker (uint32) total_size (uint16) payload_length (uint16) payload (struct iphdr) Followed by a sequence of option_id (uint16) option_length (uint16) option_value (variable, equal to option_length) Am I right to assume that: - I can define a (packed) structure for the first part, and that I can set the pointer on the data buffer which was allocated by malloc without problems ? [*] - For the second part, there are 2 cases: + integers must be read byte per byte + strings can be used directly ? [*] none of the iphdr, ip or similar structures are defined as packed in netinet/ip.h Thanks, Pierre -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
