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Date: Thu, 9 Apr 2015 19:32:13 +1000
From: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Message-ID: <20150409093213.GF30629@toto>
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Subject: Re: [Qemu-devel] [PATCH 01/14] memory: Define API for
 MemoryRegionOps to take attrs and return status
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>, Patch Tracking <patches@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>, Greg Bellows <greg.bellows@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>, Richard Henderson <rth@twiddle.net>

On Thu, Apr 09, 2015 at 10:04:39AM +0100, Peter Maydell wrote:
> On 9 April 2015 at 09:55, Edgar E. Iglesias <edgar.iglesias@gmail.com> wrote:
> > Did you consider using a struct here?
> > e.g:
> >
> > typedef struct MemTxAttrs {
> >     unsigned int secure : 1;
> >     unsigned int master_id : 10;
> >     unsigned int etc : 1;
> > } MemTxAttrs;
> >
> > I think you could still pass it by value and my understanding is
> > that the compiler will generate similar code.
> 
> We discussed this last time round, I think. Whether structs get
> passed in registers depends on the host CPU ABI/calling convention.

Ah sorry, I must have missed that response...

> 
> > I find it more readable, you ca go:
> >
> > attrs.secure = 1;
> > attrs.master_id = 0x77;
> > if (!attrs.secure)
> >
> > instead of:
> >
> > attrs |= MEMTXATTRS_SECURE
> > if (!(attrs & MEMTXATTRS_SECURE))
> >
> > etc...
> >
> > Or do you see any disadvantages with this?
> 
> I prefer the traditional integer-and-bitops approach, then you
> know what you're getting everywhere...

OK :-)

Cheers,
Edgar