Date: Wed, 22 Aug 2012 15:21:06 -0400 From: John Baldwin <jhb@freebsd.org> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-hackers@freebsd.org, freebsd-net@freebsd.org, Mitya <mitya@cabletv.dp.ua>, Warner Losh <imp@bsdimp.com>, Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Subject: Re: Replace bcopy() to update ether_addr Message-ID: <201208221521.06954.jhb@freebsd.org> In-Reply-To: <CAJ-Vmo=1cbJn3pkSvoCq7y-kEGig-h1Vxo6M5V0=b9=MkfuMRA@mail.gmail.com> References: <50324DB4.6080905@cabletv.dp.ua> <201208220802.14588.jhb@freebsd.org> <CAJ-Vmo=1cbJn3pkSvoCq7y-kEGig-h1Vxo6M5V0=b9=MkfuMRA@mail.gmail.com>
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On Wednesday, August 22, 2012 2:54:07 pm Adrian Chadd wrote: > On 22 August 2012 05:02, John Baldwin <jhb@freebsd.org> wrote: > > On Tuesday, August 21, 2012 12:34:42 pm Adrian Chadd wrote: > >> Hi, > >> > >> What about just creating an ETHER_ADDR_COPY(dst, src) and putting that > >> in a relevant include file, then hide the ugliness there? > >> > >> The same benefits will likely appear when copying wifi MAC addresses > >> to/from headers. > >> > >> Thanks, I'm glad someone noticed this. > > > > I doubt we even _need_ the ugliness. We should just use *dst = *src > > unless there is a compelling reason not to. > > Because it's not very clear? :-) I'd much prefer my array-of-things > copies to be explicit. Eh? 'struct foo *src, *dst; *dst = *src' is pretty bog-standard C. That isn't really all that obtuse. > Also, the optimisation and compiler silliness may not be THAT obvious > on intel (except when you're luigi and using netmap) but I can't help > but wonder whether the same does hold for MIPS/ARM. Getting it wrong > there will lead to some very very poor performing code. Don't you think there's a really good chance the compiler knows how to copy a structure appropriately for each architecture already? -- John Baldwin
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