Re: [Xen-devel] [PATCH v3 39/52] xen: check parameter validity when parsing command line

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.08.17 at 14:42, <jgross@xxxxxxxx> wrote:
> On 23/08/17 11:38, Jan Beulich wrote:
>>>>> On 23.08.17 at 11:30, <jgross@xxxxxxxx> wrote:
>>> On 22/08/17 13:24, Jan Beulich wrote:
>>>>>>> On 16.08.17 at 14:52, <jgross@xxxxxxxx> wrote:
>>>>> @@ -176,7 +210,8 @@ int __init parse_bool(const char *s)
>>>>>           !strcmp("on", s) ||
>>>>>           !strcmp("true", s) ||
>>>>>           !strcmp("enable", s) ||
>>>>> -         !strcmp("1", s) )
>>>>> +         !strcmp("1", s) ||
>>>>> +         !*s )
>>>>>          return 1;
>>>>
>>>> Careful with this: Taking the "iommu=" example that I've commented
>>>> on in the other patch already, much depends on what you mean to
>>>> do about the problem there: "iommu=,..." should not end up
>>>> meaning "iommu=on,...".
>>>
>>> It won't. *s will be ',' in this case.
>> 
>> Right, but as said - much depends on what you mean to do about
>> the problem in the earlier patch.
> 
> So I just hit this. And looking more thoroughly into it: today it in
> fact has exactly this meaning. iommu_enable is "1" per default. So
> specifying "iommu=,..." won't change this and has the same semantics
> as "iommu=on,...".

But that's not the interesting case. Are you saying that
"iommu=off iommu=,..." enables the IOMMU today? It doesn't
look to me as if it would.

Jan


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