RE: [Xen-devel] Status of auto_translated_mode

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> Hi, Keir,
>       Per agreement on last xen summit, now xen/ia64 
> community is working on moving dom0 from current p==m model 
> to p!=m model. First an easy way is chosen by Isaku that 
> physmap is invisible to dom0 which is instead managed by Xen. 
> After some investigation, we found that existing 
> auto_translated_mode matches our model and then would like to 
> know the status of this mode on xen/x86.
> 
> 1. First a background question, what's the major usage model 
> for auto_translated_mode? 
 
Currently, the main usage model is to support guests that haven't got
fully paravirtualied mm systems. It's also useful for a number of
research projects, such as vm fork, determinsitic replay etc.

> 2. Is auto_translated_mode only used for domU? Seems this 
> model can't apply to modified DMA interface since mfn is 
> required to manipulate physical devices.

It's currently only used for domU's, and needs to be extended to support
lookup of mfn's for DMA addresses, and to enable the backend drives to
work.

> 3. Does anyone exercise this mode recently? Is this logic 
> working or broken?

Definitely working.

>       We'd like to know which areas need to be enhanced if 
> this translated mode can be applied to dom0. That would save 
> people much time since virtual drivers together with grant 
> table have been tuned to accommodate this mode. Then this 
> translated mode may be made more generic. :-)

The first thing I would do is get physcial device access working from
for a auto_translate guest.

Ian

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