Re: Kern-control and enqueuing data

Subject: Re: Kern-control and enqueuing data

From: Josh Graessley <email@hidden>

Date: Mon, 5 Dec 2005 10:26:39 -0800

Delivered-to: email@hidden

Looking at my own reply, it's a little vague. Here are some details:

If you don't set CTL_FLAG_REG_ID_UNIT, you will be using dynamic unit numbers. This allows more than one client to attach at a time. To differentiate between the clients, you have to specify the unit number for the client that you want at the time that you enqueue data.

You can get the unit number from the connect function you specify with ctl_connect in the kern_ctl_reg structure. The sockaddr_ctl passed in will contain the unit number for that client's connection to your kernel control.

-josh

On Dec 5, 2005, at 10:16 AM, Josh Graessley wrote:

If you are using a dynamic kernel control, one where you register a name not a static id, the kernel will not fill in the unit number. The unit number at that point is undefined. You will get a unit number when a client attaches. You can track each client connection using the unit number. The control ref will always be the same, the unit number changes.

-josh

On Dec 5, 2005, at 12:39 AM, Sudarshan S wrote:

I have implemented a kern-control handler in kext. I want to pass some data to the user space program using recv queue. Whenever I tried to enqueue data using ctl_enqueuedata( ), it use to return an error code EINVAL. I was using the kern_ctl_ref and kern_ctl_reg.unit field that I got after ctl_register( ) call. Then I tried to enqueue data in setsockopt call handler (ctl_setopt) by using the parameters passed to that call and ctl_enqueuedata( ) worked fine.

Then I realized that the unit parameter passed to ctl_enqueuedata was not correct and the function was failing in kcb_find( ) call.

Is it correct to expect that kernel sets the proper value in kern_ctl_reg.unit after making ctl_register( ) call ?

Or is there any API to get the unit number by passing kern_ctl_ref ?

- Leo

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References:

>Kern-control and enqueuing data (From: Sudarshan S <email@hidden>)

>Re: Kern-control and enqueuing data (From: Josh Graessley <email@hidden>)