alignment

[Linus Torvalds]

On Sat, 15 Jul 2000, Tim Prince wrote:
>
>		 If the kernel code has been checked thoroughly to
> see that __volatile__ is required everywhere it is used, then my comment
> is superfluous for that application.

I don't know that we have checked that there are no superfluous
"volatiles". For all I know there might certainly be volatiles that could
be dropped from the kernel.

I do find it strange that gcc would emit a .align directing before a
volatile asm, and I assume that is because there is some "virtual
branch-target" there to ensure volatility or similar. I don't see the
reported behaviour on the gcc version I'm using (2.91.66), so this
behaviour is new (or maybe it's more subtle than "before every volatile",
or maybe I mis-understood the report).

[ Side comment: most of the asm's inside the kernel tend to be volatile
  for one reason or another: they tend to be synchronization points.
  Things like spinlocks, "disable interrupts" etc. I don't think the
  kernel is really all that consistent about "volatile": a number of them
  use memory clobbers instead of "volatile" to avoid getting moved
  around too much. ]

		Linus