Re: [Xen-devel] [patch] "frame number" size in hypercall ABI

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 20 Apr 2006, at 17:09, Hollis Blanchard wrote:

> So are you saying you want the patch to include Linux kernel changes?
> But not Xen changes (e.g. shadow.h) other than right at the interface?
Yes, at least where Linux is handling arrays that will get passed to a 
hypercall or the array could end up the wrong size! Of course it really 
doesn't matter for singleton values so they can safely be left as-is.
The same goes for Xen too, but I believe the arrays are only handled in 
the very hypercall functions that receive them. For example, many 
functions in common/memory.c will need to read/write values to from a 
xen_pfn_t, but these singleton values can then be passed around inside 
Xen as longs.
> I needed to change all users in libxc because they all index into
> page_array[] as unsigned long. Theoretically speaking you could have 
> the
> same problem within Linux and Xen as well. The word "unpacking" 
> suggests
> a conversion step, which is something I'm not introducing here.
The arrays aren't passed around inside Xen (I'm pretty sure). As I say 
above, we read/write one-by-one.
 -- Keir


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