Re: [Qemu-devel] [PATCH 4/4] kvm: i386: Add classic PCI device assignment

[malc]

On Tue, 28 Aug 2012, Anthony Liguori wrote:

> Blue Swirl <address@hidden> writes:
> 
> > On Tue, Aug 28, 2012 at 5:28 PM, Michael S. Tsirkin <address@hidden> wrote:
> >> On Tue, Aug 28, 2012 at 05:01:55PM +0000, Blue Swirl wrote:
> >>> On Tue, Aug 28, 2012 at 7:35 AM, Michael Tokarev <address@hidden> wrote:
> >>> > On 27.08.2012 22:56, Blue Swirl wrote:
> >>> > []
> >>> >>> +static uint32_t slow_bar_readb(void *opaque, target_phys_addr_t addr)
> >>> >>> +{
> >>> >>> +    AssignedDevRegion *d = opaque;
> >>> >>> +    uint8_t *in = d->u.r_virtbase + addr;
> >>> >>
> >>> >> Don't perform arithmetic with void pointers.
> >>> >
> >>> > There are a few places in common qemu code which does this for a very
> >>> > long time.  So I guess it is safe now.
> >>>
> >>> It's a non-standard GCC extension.
> >>
> >> So?  We use many other GCC extensions. grep for typeof.
> >
> > Dependencies should not be introduced trivially. In this case, it's
> > pretty easy to avoid void pointer arithmetic as Jan's next version
> > shows.
> 
> The standard is vague with respect void arithmetic.  Most compilers
> allow it.  A very good analysis of the standard can be found below.
> 
> http://stackoverflow.com/questions/3523145/pointer-arithmetic-for-void-pointer-in-c
> 
> BTW: can we please stop arguing about C standards.  If we currently are
> using something in QEMU that's supported by clang and GCC, it's fine and
> we ought to continue using it.

No we can not stop arguing. Besides you are wrong.

[..snip..]

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