Re: [Xen-devel] [PATCH v3 48/52] xen: add hypercall for setting parameters at runtime

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.08.17 at 11:52, <jgross@xxxxxxxx> wrote:
> On 22/08/17 13:31, Jan Beulich wrote:
>>>>> On 16.08.17 at 14:52, <jgross@xxxxxxxx> wrote:
>>> --- a/xen/include/public/sysctl.h
>>> +++ b/xen/include/public/sysctl.h
>>> @@ -1096,6 +1096,21 @@ struct xen_sysctl_livepatch_op {
>>>  typedef struct xen_sysctl_livepatch_op xen_sysctl_livepatch_op_t;
>>>  DEFINE_XEN_GUEST_HANDLE(xen_sysctl_livepatch_op_t);
>>>  
>>> +/*
>>> + * XEN_SYSCTL_set_parameter
>>> + *
>>> + * Change hypervisor parameters at runtime.
>>> + * The input string is parsed similar to the boot parameters.
>>> + */
>>> +
>>> +struct xen_sysctl_set_parameter {
>>> +    XEN_GUEST_HANDLE_64(char) params;       /* IN: pointer to parameters. 
>>> */
>>> +    uint16_t size;                          /* IN: size of parameters. */
>> 
>> The combination of length and zero terminator is always a little
>> ambiguous: I think it should be clarified in the comment what
>> behavior to expect, unless you want to either disallow
>> embedded NULs or drop the size field.
> 
> Okay.
> 
> Are you fine with e.g.:
> 
> /* Parameters are a single string terminated by a NUL byte of max. size
>    characters. Multiple settings can be specified by separating them
>    with blanks. */

Sounds good.

Jan


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