Re: [PATCH] Fix cpumap setting before passing to XEN

[Zhenzhong Duan <zhenzhong.duan@oracle.com>]

On 2016/4/12 11:35, Zhenzhong Duan wrote:
> On 2016/4/11 19:27, Wei Liu wrote:
>> On Mon, Apr 11, 2016 at 09:42:57AM +0800, Zhenzhong Duan wrote:
>>> It's tool's duty to pass a correct cpumap to XEN. On a host with 
>>> less than
>>> 64
>>> CPUS, it just shows below error.
>>>
>>> [root@localhost /]# xm vcpu-pin 3 all all
>>> Error: Cannot pin vcpu: 0 to cpu: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 
>>> 11, 12,
>>> 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 
>>> 30, 31,
>>> 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 
>>> 49, 50,
>>> 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63] - (22, 'Invalid
>>> argument')
>>>
>> This error clearly shows that the upper layer is not passing down the
>> right cpumap. So this example along won't convince me to that this is a
>> bug in python binding. It's free to reject input that it deems wrong.
>>
>> I guess the question is more or less what should it do in such
>> situation. So ...
>>
>>> The fix make it same as in xl code.
>>>
>> Is there reference to this? I guess the commit message  or mail thread
>> will shed more light on the expected behaviour.
> Calling path:
> main_vcpupin->cpurange_parse->update_cpumap_range->libxl_bitmap_set
>
> void libxl_bitmap_set(libxl_bitmap *bitmap, int bit)
> {
>     if (bit >= bitmap->size * 8)
>         return;
>     bitmap->map[bit / 8] |= 1 << (bit & 7);
> }
>
> I referenced above code. It just ignore the cpu number beyond the max 
> CPU count rather than raise an error.
Any further comments?

thanks
zduan

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