Subject: Re: [BNX2X RESUBMIT][PATCH 0/8] New driver for Broadcom 10Gb Ethernet, take two.

From: "Michael Chan" <[email-masked]>
Date: Mon, 08 Oct 2007 14:40:22 -0700

On Mon, 2007-10-08 at 12:08 -0700, Stephen Hemminger wrote:
> On Mon, 08 Oct 2007 20:34:41 +0200
> "Eliezer" <[email-masked]> wrote:
> 
> > > * The MACRO's for 64 bit stats look like they could be done with 
> > >   u64 and/or turned into inline's.
> > 
> > The MACRO's modify some of their arguments, plus they need to work on 32
> > bit machines (are 64 bit counters always available on 32 bit machines?).
> > so using an inline would allow the inline to be more readable but
> > calling it would get ugly.
> > I'm open to suggestions.
> > 
> 
> u64 exists on all platforms (including 32 bit).
> 

I think the biggest problem with these 64-bits counters (and 64-bit
addresses) is that the hardware treats them as big endian and they get
DMA'ed in big endian format.  We control the byte swap so that 32-bit
quantities will have the correct endianness, but the high and low 32-bit
words will be in the wrong spots on little endian machines.  That's why
we need to separate the high and the low words and convert them back and
forth.