From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Maydell <peter.maydell@linaro.org>
Subject: Re: [PATCH 2/2] xen: build on ARM
Date: Tue, 17 Dec 2013 18:27:37 +0000
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Anthony PERARD <anthony.perard@citrix.com>, "xen-devel@lists.xensource.com Devel" <xen-devel@lists.xensource.com>, QEMU Developers <qemu-devel@nongnu.org>
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On 17 December 2013 18:20, Stefano Stabellini
<stefano.stabellini@eu.citrix.com> wrote:
> On Tue, 17 Dec 2013, Peter Maydell wrote:
>> Per-host-architecture ifdef ladders are kind of nasty. What's this
>> code actually trying to do ? (looks like maybe "64 bit host addresses
>> vs 32 bit host addresses" ?)
>
> Almost.
> It is trying to decide how much stuff we can map into QEMU's address
> space (that is what the "Cap" is referring to). In particular consider
> the case where we are running on an ARMv8 system, dom0 and QEMU are
> 32-bit and the guest is 64-bit.

Right, so you essentially want to know the size of a host address
(that's 32 bits in a 32 bit QEMU even if the h/w is ARMv8).

#if HOST_LONG_BITS == 32
[stuff for 32 bit address space]
#else
[stuff for 64 bit address space]
#endif

thanks
-- PMM