On Thu, Dec 30, 2010 at 01:42:05PM -0800, H. Peter Anvin wrote: > On 12/30/2010 11:57 AM, Jakub Jelinek wrote: > >> > >> Would be nice if LFS would be mandatory on the new ABI, thus > >> off_t being 64bits. > > > > And avoid ambiguous cases that x86-64 ABI has, e.g. whether > > caller or callee is responsible for sign/zero extension of arguments, to > > avoid the need to sign/zero extend twice, etc. > > > > Ehwhat? x86-64 is completely unambiguous on that point; the i386 one is > not.
It is not, sadly, see http://gcc.gnu.org/PR46942 >From what I can see the psABI doesn't talk about it, GCC usually sign/zero extends on both sides (exception is 32-bit arguments into 64-bit isn't apparently sign/zero extended on the caller side when doing tail calls), from what I gathered LLVM expects the caller to sign/zero extend (which is incompatible with GCC tail calls then), not sure about ICC, and kernel probably expects for security reasons that the callee sign/zero extends. Jakub
