Messages in this thread | | | Date | Tue, 21 Jun 2011 16:41:59 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute |
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On Tue, 21 Jun 2011, Alan Stern wrote:
> On Mon, 20 Jun 2011, Nicolas Pitre wrote: > > > > We don't fall into any of these cases, and therefore as you say, we > > > don't need packed. Arnd and I have both explained this. So why do you > > > keep arguing that we do need it? > > > > Please show me where I keep arguing that you need it? > > Not explicitly perhaps. But you did write: > > > Doesn't mean that because it used to work that it is strictly correct. > > Wouldn't be the first time that a GCC upgrade broke the kernel because > > the kernel wasn't describing things properly enough. > > which strongly implies that "packed" is needed. You also wrote:
In this case ...
> > Yes, but that's a consequence of not being able to access those fields > > in their naturally aligned position anymore. Hence the addition of the > > align attribute to tell the compiler that we know that the structure is > > still aligned to a certain degree letting the compiler to avoid > > byte-oriented instructions when possible. > > which is predicated on the assumption that "packed" is needed.
... and also in this case, I was talking about proper use of the packed attribute in general, not at all about a specific case. I wanted to provide a broader view to some people who expressed doubts and misunderstanding in the hope that the archive could keep this knowledge base available.
I apologize if that wasn't clear to you.
Nicolas
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