Re: [lwip-users] [PATCH] fix warning for gcc and possible unaligned access

[Timmy Brolin]

Pedro Alves wrote:

> address@hidden wrote:
>
> > Hi,
> > Why not just replace the lines
> >
> >     *(struct ip_addr2 *)&sipaddr = hdr->sipaddr;
> >     *(struct ip_addr2 *)&dipaddr = hdr->dipaddr;
> > with
> >     sipaddr = *(struct ip_addr *)&hdr->sipaddr;
> >     dipaddr = *(struct ip_addr *)&hdr->dipaddr;
>
> Because if hdr->sipaddr is unaligned and the architecture doesn't 
> support unaligned accesses, like many RISCs do, the result is undefined. 

Are you sure that it can become unaligned?
There is code in place in lwip to guarantee header alignment...