[Xen-devel] Re: user/hypervisor address space solution

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Feb 15, 2006, at 5:23 AM, Keir Fraser wrote:
> On 15 Feb 2006, at 10:48, Hollis Blanchard wrote:
>
> > I will be busy for a week or so, but I will try to come up with a 
> > patch
> > that converts x86 and ia64 and all common code to the proposed API:
> >         get_user_offset(val, base, offset)
> >         put_user_offset(val, base, offset)
> >         get_user_array(val, array, index)
> >         put_user_array(val, array, index)
> >         copy_to_user(to, from, len)
> >         copy_from_user(to, from, len)
> > ... plus __ variants of all of these, with identical arguments
> > ... plus arch-specific get/put_user for e.g. xen/arch/x86/domain.c,
> > since some of those usages don't seem to fit above.
> >
> > If you don't like the API, please speak up now.
> Should be called get_guest/put_guest/copy_from_guest/copy_to_guest. 
> Better names, and the arch-specific old functions can still keep their 
> old names.
"guest" not "domain"? Either way is fine with me. If we do leave the 
old names in, though, I'm sure people will slip them into common 
code...
> What's the difference between foo_offset() and foo_array()?
Just convenience: many (most?) users of get/put_user() are to an 
address like "&array[index]". If we only had _offset(), those callers 
would look like:
        put_user(val, array, sizeof(*array)*index);
Actually that doesn't look too bad. :) If you're ok with that, we can 
stick with just the "offset" variant.
--
Hollis Blanchard
IBM Linux Technology Center


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