Re: [Xen-devel] [PATCH 04/13] xen: sync public headers

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Wei Liu [mailto:wei.liu2@xxxxxxxxxx]
> Sent: 07 February 2013 11:58
> To: Paul Durrant
> Cc: Wei Liu; Konrad Rzeszutek Wilk; David Vrabel; Ian Campbell;
> jbeulich@xxxxxxxx; xen-devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH 04/13] xen: sync public headers
> 
> On Thu, 2013-02-07 at 09:22 +0000, Paul Durrant wrote:
> > > -----Original Message-----
> > [snip]
> > > > > > -#define NR_EVENT_CHANNELS (sizeof(unsigned long) *
> > > > > > sizeof(unsigned long) * 64)
> > > > > > +#define NR_EVENT_CHANNELS_L2 (sizeof(unsigned long) *
> > > > > > +sizeof(unsigned long) * 64)
> > > > >
> > > > > We did a bit of header change to make the ARM code always use
> > > > > 'unsinged long long' on 32-bit (so it is a nice 8-bytes) and
> > > > > 'unsigned long' on 64-bit. This was all done using the xen_pfn_t
> > > > > and
> > > xen_mfn_t typdefs.
> > > > >
> > > > > Any chance you can do that here? That way on ARM - irregardless
> > > > > if it is 32-bit or 64-bit it is always of the 64-bit size?
> > > > >
> > > >
> > > > I don't think so. The reason to use unsigned long here is to
> > > > guarantee each selector (in 2-level case there is only L1
> > > > selector) fits into a word.
> > >
> >
> > That's still going to be a problem with Windows drivers. Unfortunately
> MSVC uses a 64-bit model where longs are still 32-bit. The only thing that is
> word size is a pointer. Any chance we can use uintptr_t rather than an
> unsigned long? (At the moment I have to sed all the public headers to
> replace long with LONG_PTR and it's a PITA).
> >
> 
> TBH I don't know much about Windows. But are you suggesting replace all
> the relevant bit in the header or just the specific event channel interface?
> 

I was just pointing out that assumption that unsigned long == native word size 
does not hold for 64-bit Windows. So, if we're adding something new can we 
avoid use of unsigned long and use an abstract type defined to be the native 
word size?

  Paul
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