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Re: [libvirt] [PATCH] Convert qemu command line flags to 64-bit int



On Wed, Feb 10, 2010 at 10:51:31AM +0000, Daniel P. Berrange wrote:
> On Wed, Feb 10, 2010 at 11:45:45AM +0100, Matthias Bolte wrote:
> > 2010/2/10 Daniel Veillard <veillard redhat com>:
> > > On Tue, Feb 09, 2010 at 07:04:24PM +0000, Daniel P. Berrange wrote:
> > >> The QEMU flags are commonly stored as a signed or unsigned int,
> > >> allowing only 31 flags. This limit is rather close, so to aid
> > >> future patches, change it to a 64-bit int
> > >>
> > >> * src/qemu/qemu_conf.c, src/qemu/qemu_conf.h, src/qemu/qemu_driver.c,
> > >>   tests/qemuargv2xmltest.c, tests/qemuhelptest.c, tests/qemuxml2argvtest.c:
> > >>   Use 'unsigned long long' for QEMU flags
> > >> ---
> > 
> > >
> > >  ACK, that was something I was about to look at :-)
> > > hopefully the enum definition for the flags will allow to go over
> > > 32 bits too, I think the patch should also change all the
> > > QEMUD_CMD_FLAG_ in /src/qemu/qemu_conf.h to be redefined from
> > > (1 << x) into (1UUL << x),
> > >
> > > Daniel
> > >
> > 
> > I missed the fact that the flags are defined as enum members. This
> > maybe an issue. IIRC enum members are ints. We should test this to
> > make sure it works as expected on 32bit and 64bit systems.
> 
> We're not ever declaring instances of the enum type, only using it as a
> convenient way to define the constants. So provided we add '1UUL' as
> DV suggests, we should be fine.

I just tested and confirmed that on 32-bit when we start adding values
to the enum >= 32 we will need to make it use 1ULL. The compiler actually
identifies & warns about this so you can't miss it :-)


Daniel
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