* Sasha Levin <[email protected]> wrote:
> On Fri, 2011-05-13 at 10:19 +0200, Ingo Molnar wrote:
> > FYI, the tools/kvm build still fails on 32-bit:
> >
> > cc1: warnings being treated as errors
> > qcow.c: In function ‘qcow1_write_sector’:
> > qcow.c:307: error: comparison between signed and unsigned integer
> > expressions
> > make: *** [qcow.o] Error 1
> > make: *** Waiting for unfinished jobs....
> >
> > using:
> >
> > gcc version 4.4.4 20100630 (Red Hat 4.4.4-10) (GCC)
> >
> > The patch below addresses them but i haven't tested it beyond checking that
> > it
> > builds.
> >
> > The double cast of userspace_addr is doubly sad - it highlights our
> > 32-bitness
> > problems which are visible in the guest_pfn_to_host() function as well.
>
> KVM API uses 64-bit addresses no matter the host bitness, so we can't
> really get around doing these sort of casts.
that bit is OK - the KVM ABI has to be for the largest bit width.
Note that this kind of ABI compatibility allows (in theory) to run a 32-bit kvm
binary on a 64-bit kernel, and still everything would work despite hypervisor
user-space being 32-bit.
So the cast to (unsigned long) is fine and clean.
Thanks,
Ingo
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