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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-02-08 at 16:06 +0000, Paul Durrant wrote:
> > -----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?

Probably ought to be the existing xen_ulong_t.

Ian.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel