On Tue, 2007-02-13 at 15:35 +1100, Stephen Rothwell wrote: > OK, I have thought about this some more and I *think* the only > architecture that needs compat_sys_epoll_ctl or compat_sys_epoll_wait is > ia64 where the 64 bit version of struct epoll_event is different from the > 32 bit version. On x86_64, the struct is explictly packed (so it is the > same as the 32 bit version) and on all the other 64 bit architectures the > alignment of the u64 is the same as the equivalent 32 bit version. > > Since ia64 already has its own version of these two, we only have to > worry about epoll_pwait and then the struct epoll_event is only a problem > for ia64. > > Am I right? (I have cc'd linux-arch for guidance.)
Not for parisc at the instruction level. In narrow mode (32 bit mode), a u64 load has to be done by two 32 bit loads which gives it a 4 byte alignment requirement. In wide mode (64 bit mode) the 64 bit load instruction explicitly requires 8 byte alignment, so our u64 alignment requirements are different. However, this is from the machine code point of view. I can't say that gcc doesn't enforce an artificial 8 byte alignment of u64 in narrow mode, so I'll defer to the gcc experts on that one. James - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
