Re: [Xen-devel] netfront: rx->offset: 12, size: 4294967295

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> > My suspicion is that, strictly speaking, the assignment of 1 to
> > copying_receiver is invalid because a single-bit bitfield can only hold
> > the values -1 and 0. Older gcc perhaps mapped 1 to -1, but 4.2.0 is
> > mapping 1 to 0 (or choosing to do that as an optimisation, since it has
> > the choice, and hence can simplify the code to always write zero in this
> > case). That sucks.
>
> That's why we always use unsigned for bitfields in Linux.

I found a load of bitfields that we ought to consider unsigned-ifying when I 
ran sparse over the tree.

I guess I should try and get a patch sent out proactively, maybe that'll head 
off similar problems in future.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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