AMD vol2 p295 says that long mode iret requires a 64-bit
rex prefix,

now AMD vol 3 p16 talks about rex, it says
there are 4 flags rex.w, rex.r, rex.x, rex.b

no idea how you do this with fasm,

how do I do a 64 bit no-op interrupt handler?

fasm does not accept eg:



anyone know the correct way to do this?

can I do it via a db value eg
"db 66h" is the "opsize" prefix

I think you can do iretd and iretq and the prefix added is not 66h but 48h

ok, I tried it just now and it looks correct

the hex of "iretq" is 48CFh which appears to be right,


with interrupt handlers where there is an error code
do I have to pop the error code before iretq or
is that done automatically?

or can I do it both ways either pop or not pop?

one other thing: how many interrupt handlers are required?

vectors 0 up to 255 or less?

I want to create a full set of no-op handlers,