[PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute

On Mon, 20 Jun 2011, Arnd Bergmann wrote:

On Monday 20 June 2011 20:39:02 Alan Stern wrote:

quoted

On Mon, 20 Jun 2011, Alexander Holler wrote:

quoted

I see it that way: packed is needed to be sure that at least for struct 
ehci_regs there are no padding bytes inbetween the members.

But is it really needed?

No. When the structure is marked packed, it's broken because it relies
on undefined behavior. If it's not packed, there is no problem.

quoted

quoted

It might 
work without, but that depends on the compiler (-version, architecture, 
whatever).

Have there ever been any combinations of compiler, version, 
architecture, whatever, that had unwanted padding bytes in this 
structure?

Only on compilers that are not able to build Linux kernels anyway.

Just as I thought.  There's no reason to accept the proposed patch; 
we're fine the way we are now.

Alan Stern