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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> 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.

> 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).

Jan


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