Some confusing code of the kernel

[Yuxin Ren]

Thank you very much for your detail reply.
It is really useful and helpful.


On Thu, May 29, 2014 at 9:17 AM, Marcus Hähnel <
mhaehnel at os.inf.tu-dresden.de> wrote:

> On 2014-05-29 18:22, Yuxin Ren wrote:
>
>> On Tue, May 27, 2014 at 11:44 PM, Marcus Hähnel
>> <mhaehnel at os.inf.tu-dresden.de> wrote:
>>
>>  On 2014-05-28 03:59, Yuxin Ren wrote:
>>>
>>>  Thank you very much.
>>>> But how can I know which file is compiled?
>>>>
>>>
> What do you mean with 'how can I know'?
> Do you mean how you can set it?
>
> The menuconfig option is [Kernel options] -> [No virtually mapped array
> for cap tables], which is only visible if you enable experimental features
> in the main menu.
>
> Or do you mean how you can find out which one is compiled?
>
> I already pointed you to src/Modules.generic which has an if clause that
> decides which one to use based on the config option in lines 33 and
> following. The Modules.generic file is included by the build system during
> the build process.
>
> Does that answer your Question?
>
> - Marcus
>
>
>  This is decided during build time based on your configuration. The vuild
>>> system decides which file to build based on the CONFIG_VIRT_OBJ_SPACE
>>> setting. See src/Modules.generic.
>>>
>>> - Marcus
>>>
>>
>>      Thanks a lot.
>>     But can you tell me a little in detail which kernel compile
>> configuration decides  this?
>>     I am using x86 and ia32..
>>
>>    Best
>>
>>  On Wed, May 28, 2014 at 6:55 AM, Adam Lackorzynski
>>>> <adam at os.inf.tu-dresden.de> wrote:
>>>>
>>>>  Hi,
>>>>>
>>>>> On Tue May 27, 2014 at 13:51:31 -0800, Yuxin Ren wrote:
>>>>>
>>>>>  Now I am learning the kernel code of Fiasco.
>>>>>> But as I do not know much about C++, I feel confused about some code.
>>>>>>
>>>>>
>>>>> Some C++ knowledge is required I think...
>>>>>
>>>>>  In the file obj_space-virt.cpp, we have such code
>>>>>> EXTENSION class Generic_obj_space : Obj_space_virt<Generic_obj_
>>>>>> space<SPACE>
>>>>>>
>>>>>>
>>>>>>>
>>>>>> And similarly, in the file obj_space-phys.cpp, we have
>>>>>> EXTENSION class Generic_obj_space : Obj_space_phys<Generic_obj_space<
>>>>>> SPACE
>>>>>>
>>>>>>
>>>>>>>>
>>>>>> 1. What's the meaning of these tow line code? Does it mean that the
>>>>>> class
>>>>>> Generic_obj_space
>>>>>> inherit from both class Obj_space_virt and class Obj_space_phys?
>>>>>>
>>>>>
>>>>> It inherits from just Obj_space_phys which however takes another class
>>>>> as a parameter to implement some specific functionality at compile
>>>>> time.
>>>>>
>>>>>  uch as lookup_local method. When such a method is called, how can I
>>>>>> know
>>>>>> which class is invoked?
>>>>>>
>>>>>> That depends on the type of the object the method is called on. In
>>>>>> this
>>>>>> particul
>>>>>>
>>>>> obj_space-*.cpp, only one file of the two files is
>>>>>
>>>>> compiled, so only one version of Generic_obj_space can ever exist.
>>>>>
>>>>> Adam
>>>>> --
>>>>> Adam                 adam at os.inf.tu-dresden.de
>>>>>   Lackorzynski         http://os.inf.tu-dresden.de/~adam/ [1] [1]
>>>>>
>>>>>
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>>>>>
>>>>
>>>> Links:
>>>> ------
>>>> [1] http://os.inf.tu-dresden.de/~adam/ [1]
>>>> [2] http://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers [2]
>>>>
>>>>
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>>
>>
>> Links:
>> ------
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>
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