Re: [Xen-devel] [PATCH v7] x86/mem-sharing: mem-sharing a range of memory

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

On Tue, Jul 19, 2016 at 10:55 AM, Andrew Cooper
<andrew.cooper3@xxxxxxxxxx> wrote:
> On 19/07/16 17:54, Tamas K Lengyel wrote:
>> On Tue, Jul 19, 2016 at 10:49 AM, Andrew Cooper
>> <andrew.cooper3@xxxxxxxxxx> wrote:
>>> On 19/07/16 17:27, Tamas K Lengyel wrote:
>>>>>> +{
>>>>>> +    int rc = 0;
>>>>>> +    shr_handle_t sh, ch;
>>>>>> +    unsigned long start =
>>>>>> +        range->_scratchspace ? range->_scratchspace : range->start;
>>>>> This can be shortened to "unsigned long start = range->_scratchspace ?:
>>>>> range->start;" and fit on a single line.
>>>> I'm not that familiar with this style of the syntax, does that have
>>>> the effect of setting start = _scratchspace when _scratchspace is not
>>>> 0?
>>> It is a GCC extension
>>> https://gcc.gnu.org/onlinedocs/gcc-6.1.0/gcc/Conditionals.html which
>>> allows you to omit the middle parameter if it is identical to the first.
>> Are we OK with using syntax that is based on a compiler extension? I
>> recall some cases where that was frowned upon (like using the 0b
>> prefix).
>
> We already use these all over the place.
>
> The problem with 0b is that it isn't supported in all versions of GCC we
> support.
>

Alright, sound good!

Thanks,
Tamas

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