Re: [Xen-devel] [PATCH-for-4.13 v5] Rationalize max_grant_frames and max_maptrack_frames handling

[George Dunlap <George.Dunlap@xxxxxxxxxx>]

> On Nov 29, 2019, at 4:07 PM, Ian Jackson <ian.jackson@xxxxxxxxxx> wrote:
> 
> Durrant, Paul writes ("RE: [PATCH-for-4.13 v5] Rationalize max_grant_frames 
> and max_maptrack_frames handling"):
>>> -----Original Message-----
>>> From: Ian Jackson <ian.jackson@xxxxxxxxxx>
> ...
>>> Is there some reason we wouldn't use ~0 to mean default ?
>>> 
>>> In the tools area we normally spell this as
>>>     ~(some appropriate type)0
>>> to make sure it has the right width.  But if we know the type and it
>>> is of fixed length, as here, 0xffffffffu is OK too.
>>> 
>>>> The type change here makes me feel a bit uncomfortable, though in
>>>> practice it may not matter. I don't see anyone would specify a value
>>>> that would become negative when cast from uint32 to integer.
>>> 
>>> The problem with the type change is that in principle we have to audit
>>> all the places the variables are used.
>> 
>> Can a toolstack maintainer please come up with a concrete suggestion as to 
>> what the patch should do then? It's now at v6 and time is short.
> 
> I think our proposal is to drop the type change, continue to use
> uint32_t everwhere for these values, and specify the "use default"
> value to be all-bits-set.

I tried to suggest something like this, but Jan didn’t like it for some reason.

 -George
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