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

From: Arnd Bergmann
Date: Mon Jun 20 2011 - 16:11:09 EST

On Monday 20 June 2011 20:39:02 Alan Stern wrote:
> On Mon, 20 Jun 2011, Alexander Holler wrote:
> > 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.

> > 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.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at