Re: [PATCH 01/13] kdbus: add documentation

[David Herrmann]

Hi

On Mon, Jan 26, 2015 at 5:45 PM, Michael Kerrisk (man-pages)
<mtk.manpages@xxxxxxxxx> wrote:
> On 01/26/2015 04:26 PM, Tom Gundersen wrote:
>> On Mon, Jan 26, 2015 at 3:42 PM, Michael Kerrisk (man-pages)
>> <mtk.manpages@xxxxxxxxx> wrote:
>>> 2. Is the API to be invoked directly by applications or is intended to
>>>    be used only behind specific libraries? You seem to be saying that
>>>    the latter is the case (here, I'm referring to your comment above
>>>    about sd-bus). However, when I asked David Herrmann a similar
>>>    question I got this responser:
>>>
>>>       "kdbus is in no way bound to systemd. There are ongoing efforts
>>>        to port glib and qt to kdbus natively. The API is pretty simple
>>>        and I don't see how a libkdbus would simplify things. In fact,
>>>        even our tests only have slim wrappers around the ioctls to
>>>        simplify error-handling in test-scenarios."
>>>
>>>    To me, that implies that users will employ the raw kernel API.
>>
>> The way I read this is that there will (probably) be a handful of
>> users, namely the existing dbus libraries: libdus, sd-bus, glib, Qt,
>> ell, and maybe a few others. However, third-party developers will not
>> know/care about the details of kdbus, they'll just be coding against
>> the dbus libraries as before (might be minor changes, but they
>> certainly won't need to know anything about the kernel API). Similarly
>> to how userspace developers now code against their libc of choice,
>> rather than use kernel syscalls directly.
>
> Thanks, Tom, for the input. I'm still confused though, since elsewhere
> in this thread David Herrmann said in response to a question of mine:
>
>     I think we can agree that we want it to be generically useful,
>     like other ipc mechanisms, including UDS and netlink.
>
> Again, that sounds to me like the vision is not "a handful of users".
> Hopefully Greg and David can clarify.

I only expect a handful of users to call the ioctls directly. The
libraries that implement the payload-marshaling, in particular. It's a
similar situation with netlink.

Thanks
David
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