Re: [Xen-devel] [PATCH v2 3/3] tools: introduce parameter max_wp_ram_ranges.

["Yu, Zhang" <yu.c.zhang@xxxxxxxxxxxxxxx>]

On 1/27/2016 10:32 PM, Jan Beulich wrote:
> > > > On 27.01.16 at 15:13, <yu.c.zhang@xxxxxxxxxxxxxxx> wrote:
> > About the default value:
> >     You are right. :) For XenGT, MAX_NR_IO_RANGES may only work under
> > limited conditions. Having it default to zero means XenGT users must
> > manually configure this option. Since we have plans to push other XenGT
> > tool stack parameters(including a GVT-g flag), how about we set this
> > max_wp_ram_ranges to a default one when GVT-g flag is detected, and
> > till then, max_wp_ram_ranges is supposed to be configured explicitly for
> > XenGT?
> Sounds reasonable, and in line with what iirc was discussed on
> the tool stack side.
Great, and thanks.

> > About the truncation issue:
> >     I do not quite follow. Will this hurt if the value configured does
> > not exceed 4G? What about a type cast?
> A typecast would not alter behavior in any way. And of course
> a problem only arises if the value was above 4 billion. You either
> need to refuse such values while the attempt is made to set it.
> or you need to deal with the full range of possible values. Likely
> the former is the better (and I wonder whether the upper
> bound shouldn't be forced even lower than 4 billion).
Oh, I see. A check with the upper bound sounds better. Using 4G as the
upper bound is a little conservative, but I do not have any better
criteria right now. :)

> Jan
Thanks
Yu

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