How to exchange data between Kernel & User Space

How to exchange data between Kernel & User Space

[Gangadhar Uppala]

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Hi All,
    Here we are in need of a design decision . The problem is as follows:

We are writing device driver for network adapter, as part of this we need to
exchange some information between user and kernel(driver) and vice versa. As
i know this can be implemented using IOCTLs. Please suggest an alternative
approach for this.

Please keep a copy for me, because i am not subscriber to this list.

Thanks
Gangadhar


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Re: How to exchange data between Kernel & User Space

[Matti Aarnio]

On Wed, Sep 26, 2001 at 09:21:25AM +0530, Gangadhar Uppala wrote:
> Hi All,
>     Here we are in need of a design decision . The problem is as follows:
> 
> We are writing device driver for network adapter, as part of this we need to
> exchange some information between user and kernel(driver) and vice versa. As
> i know this can be implemented using IOCTLs. Please suggest an alternative
> approach for this.

   Why the system supplied standard set of ioctls isn't enough ?
   Or is not extendible ?

   Something very special you need to do ?
   Is high bandwidth needed at this communication ?

   For normal network traffic the communication goes via kernel internal
   packet reception path, but if you want to do something totally different,
   suggesting alternates needs an idea of what you are aiming at.

> Please keep a copy for me, because i am not subscriber to this list.
> 
> Thanks
> Gangadhar

/Matti Aarnio

Re: How to exchange data between Kernel & User Space

[Kirill Ratkin]

Use mmap and see exmaple here:
http://www.kernelnewbies.org/code/mmap/

Regards,

--- Matti Aarnio <matti.aarnio@zmailer.org> wrote:
> On Wed, Sep 26, 2001 at 09:21:25AM +0530, Gangadhar
> Uppala wrote:
> > Hi All,
> >     Here we are in need of a design decision . The
> problem is as follows:
> > 
> > We are writing device driver for network adapter,
> as part of this we need to
> > exchange some information between user and
> kernel(driver) and vice versa. As
> > i know this can be implemented using IOCTLs.
> Please suggest an alternative
> > approach for this.
> 
>    Why the system supplied standard set of ioctls
> isn't enough ?
>    Or is not extendible ?
> 
>    Something very special you need to do ?
>    Is high bandwidth needed at this communication ?
> 
>    For normal network traffic the communication goes
> via kernel internal
>    packet reception path, but if you want to do
> something totally different,
>    suggesting alternates needs an idea of what you
> are aiming at.
> 
> > Please keep a copy for me, because i am not
> subscriber to this list.
> > 
> > Thanks
> > Gangadhar
> 
> /Matti Aarnio
> -
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Re: How to exchange data between Kernel & User Space

[Matti Aarnio]

On Tue, Sep 25, 2001 at 11:11:24PM -0700, Kirill Ratkin wrote:
> Use mmap and see exmaple here:
> http://www.kernelnewbies.org/code/mmap/

	That is partial possibility, but the example is
	incomplete, and dangerous in case the machine
	has more than about 800 MB memory. (E.g. it has,
	and uses, HIGHMEM facility.)

	It is also completely wrong approach in case
	the interface does not need to be high bandwidth
	payload delivering directly into user space,
	but e.g. control some aspects of hardware.
	("network interface" sounds, to me, very much
	 of NETDEV class device at which MMAP tricks
	 in general are wrong.)

	The person asking for pointers didn't give
	enough details for good advice.  Supplying
	the many ropes which Linux has for hanging
	oneself is not a good advice.

> Regards,

  /Matti Aarnio