Re: [Qemu-devel] [PATCH] qdev-monitor.c: Add device id generation

[Programmingkid]

On Aug 25, 2015, at 2:30 PM, Markus Armbruster wrote:

> Programmingkid <address@hidden> writes:
> 
>> On Aug 25, 2015, at 11:33 AM, Peter Maydell wrote:
>> 
>>> On 25 August 2015 at 16:25, Programmingkid <address@hidden> wrote:
>>>> On Aug 25, 2015, at 8:42 AM, Markus Armbruster wrote:
>>>>> Eric Blake <address@hidden> writes:
>>>>> 
>>>>>> On 08/24/2015 12:53 PM, Programmingkid wrote:
>>>>>>> +/* USB's max number of devices is 127. This number is 3 digits long. */
>>>>>>> +#define MAX_NUM_DIGITS_FOR_USB_ID 3
>>>>> 
>>>>> This limit makes no sense to me.
>>>> 
>>>> The limit is used to decide how many characters the device_id
>>>> string is going to have.
>>>> Three digits would be 0 to 999 device ID's would be supported. I
>>>> can't imagine
>>>> anyone spending the time to add that many devices.
>>> 
>>> Arbitrary limits are often a bad idea, especially when
>>> they're easy to avoid, as here.
>> 
>> Knowing QEMU's limits can save the user from crashes and other
>> problems. There is
>> only a finite amount of memory available to QEMU. 
> 
> Repeat N times:
>    device_add FOO,id=hot
>    device_del hot
> 
> Memory usage independent of N (unless we leak, but that would be a bug).
> 
> [...]

Good example.