Andi Kleen a écrit : > Christoph Lameter <clameter@xxxxxxx> writes: > >> The problem is that offsets relative to %gs or %fs are limited by the >> small memory model that is chosen. > > Actually they are not. If you really want you can do > movabs $64bit,%reg ; op ...,%gs:(%reg) > It's just not very efficient compared to small (or rather kernel) model > and also older binutils didn't support large model. > I am not sure Christoph was refering to actual instructions. I was suggesting using for static percpu (vmlinux or modules) : vmlinux : (offset31 computed by linker at vmlinux link edit time) incl %gs:offset31 modules : (offset31 computed at module load time by module loader) incl %gs:offset31 (If we make sure all this stuff is allocated in first chunk) And for dynamic percpu : movq field(%rdi),%rax incl %gs:(%rax) /* full 64bits 'offsets' */ I understood (but might be wrong again) that %gs itself could not be used with an offset > 2GB, because the way %gs segment is setup. So in the 'dynamic percpu' case, %rax should not exceed 2^31 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
