64-bit write() system call

[Bob Plantz]

On Wed, 2008-03-19 at 18:59 -0700, Brian Dessent wrote:
> The design of the x86_64 instruction set made some compromises for speed
> and for keeping the size of the instructions down, namely that there are
> very few instructions that take a full 64 bit operand... in fact
> 'movabs' is the only one.  All the rest all take 32 bit operands and the
> address is calculated through either sign extension or as
> %rip-relative.  This is actually not a big deal because these days most

I read that, but then how can I do the 64-bit immediate here:

  11 0004 49BAEFCD 	        movq    $0x1234567890abcdef, %r10  # 64-bit
immediate
  11      AB907856 
  11      3412
  12 000e 41BB7856 	        movl    $0x12345678, %r11d         # 32-bit
immediate
  12      3412
  13 0014 6641BC34 	        movw    $0x1234, %r12w             # 16-bit
immediate
  13      12
  14 0019 41B512   	        movb    $0x12, %r13b               # 8-bit
immediate

Thank you for your quote from x86_64 ELF. It's making sense to me now. I
guess I jumped the gun a little when posing my question. I should've
read some more. But I was getting stuck in my research trying to figure
out what to read. You've helped me a great deal.

Bob