2011/12/1 Mauro Carvalho Chehab<mchehab@xxxxxxxxxx>:On 01-12-2011 12:58, HoP wrote:
Hi,
let me ask you some details of your interesting idea (how to
achieve the same functionality as with vtunerc driver):
[...]
The driver, as proposed, is not really a driver, as it doesn't support
any
hardware. The kernel driver would be used to just copy data from one
userspace
Please stop learning me what can be called driver and what nope.
Your definition is nonsense and I don't want to follow you on it.
application to the other. The same result could be obtained in userspace,
by implementing a library. Such library could even use LD_PRELOAD to
support
binary only applications, like what libv4l does. In terms of performance,
such library would probably perform better than a kernel driver, as
there's
no need to do context switching for each call, and no need to talk with a
device (where kernel outperforms userspace). Also, depending on how such
library
is implemented, double buffering might be avoided.
So, from architectural POV, this code should be written as an userspace
library.
BTW, alsa also came with the same results, years ago, as audio remote
streaming is supported via userspace tools, like pulseaudio.
Can you show me, how then can be reused most important part
of dvb-core subsystem like tuning and demuxing?
Why do you need to implement it? Just forward the requests to the machine
with the real driver.
Or do you want me
to invent wheels and to recode everything in the library?
Kernel code is GPLv2. You can use its code on a GPLv2 licensed library.
I see. So if you think it is nice to get dvb-core, make a wrapper around
to get it usable in userspace and maintain totally same functionality
by myself then I say it is no go. If it looks for you like good idea
I must disagree. Code duplication? Two maintaners? That is crazy idea man.
Of course
I can be wrong, I'm no big kernel hacker. So please show me the
way for it. BTW, even if you can find the way, then data copying
from userspace to the kernel and back is also necessery.
See libv4l, at v4l2-utils.git (at linuxtv.org).
I really
don't see any advantage of you solution.
And I can't see any advantage on yours ;) Putting something that belongs
to userspace into kernelspace just because it is easier to re-use the
existing code inside the kernel is not a good argument.
It is only your POV that it should be in userspace.
Creating additional code which not only enlarge code size by 2
but I think by 10 is really not good idea. And it get no advantage
only disadvantages.
Don't get me wrong but if you want to submit a code to be merged
on any existing software (being open source or not), you should be
prepared to defend your code and justify the need for it to the
other developers.
Sure. I was prepared for technical disscussion, but was fully suprised
that it was not happend (ok, to be correct, few guys are exception, like
Andreas and few others. I really appreciate it).
So, my question was still not answered: "Can be driver NACKed only
because of worrying about possible misuse?"