Re: [Xen-devel] [PATCH 3/3] tools: introduce parameter max_ranges.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jan 20, 2016 at 01:02:39PM +0800, Yu, Zhang wrote:
> 
> 
> On 1/20/2016 11:58 AM, Tian, Kevin wrote:
> >>From: Yu, Zhang [mailto:yu.c.zhang@xxxxxxxxxxxxxxx]
> >>Sent: Wednesday, January 20, 2016 11:33 AM
> >>>As a feature this write-protection has nothing to be GPU virtualization 
> >>>specific.
> >>>In the future the same mediated pass-through idea used in XenGT may be
> >>>used on other I/O devices which need to shadow some structure w/ 
> >>>requirement
> >>>to write-protect guest memory. So it's not good to tie this to either XenGT
> >>>or GTT.
> >>>
> >>Thank you, Kevin.
> >>Well, if this parameter is not supposed to be xengt specific, we do not
> >>need to connect it with any xengt flag such as ."vgt=1" or "GVT-g=1".
> >>Hence the user will have to configure the max_wp_ram_ranges himself,
> >>right?
> >>
> >
> >Not always. The option can be configured manually by the user, or
> >automatically set in the code when "vgt=1" is recognized.
> 
> OK. That sounds more reasonable. :)
> To give a summary, I'll do the following changes in next version:
> 
> 1> rename this new parameter to "max_wp_ram_ranges", then use this
> parameter as the wp-ram rangeset limit, for the I/O rangeset, keep
> MAX_NR_IO_RANGES as its limit;
> 2> clear the documentation part;
> 3> define a LIBXL_HAVE_XXX in libxl.h to indicate a new field in the
> build info;
> 4> We do not introduce the xengt flag by now, and will add code to
> automatically set the "max_wp_ram_ranges" after this flag is accepted
> in the future.
> 
> Does anyone have more suggestions? :)
> 

Ian posted an enquiry earlier:

"Could we use something like one of those to cause the t/stack to just
DTRT without the user having to micromanage the amount of pages which
are allowed to have this property?"

Is that possible?

Wei.


> B.R.
> Yu
> >
> >Thanks
> >Kevin
> >

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