Re: [Qemu-devel] [PATCH 1/2] memory: allow zero size for adjust_endianness()

[Michael S. Tsirkin]

On Thu, Aug 27, 2015 at 01:27:54PM +0100, Peter Maydell wrote:
> On 27 August 2015 at 13:25, Michael S. Tsirkin <address@hidden> wrote:
> > On Thu, Aug 27, 2015 at 01:20:52PM +0100, Peter Maydell wrote:
> >> On 27 August 2015 at 13:17, Michael S. Tsirkin <address@hidden> wrote:
> >> > Basically the point is that ABI is extended to make
> >> > ioeventfd with len = 0 mean "any length".
> >> > 0 is thus not meaningless anymore.
> >>
> >> But how can you do adjustment for incorrect endianness
> >> if you don't know the size of the data that you're
> >> trying to work with? That's why this switch insists
> >> that the size is 1, 2, 4 or 8.
> 
> > For kvm at least, "any length" implies "any data".
> > So data is eventually discarded, we don't really need
> > to adjust it for endian-ness.
> 
> I'm still confused. If you have data it needs to be
> adjusted. If we're not actually doing anything with
> the data why are we calling this function in the first
> place?
> 
> -- PMM

I guess you could skip calls to adjust_endianness when len == 0,
that should work just as well.

-- 
MST