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

["Yu, Zhang" <yu.c.zhang@linux.intel.com>]

On 1/27/2016 10:32 PM, Jan Beulich wrote:
>>>> On 27.01.16 at 15:13, <yu.c.zhang@linux.intel.com> 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