Re: kernel panic with new pseudo device

[Michael <macallan%netbsd.org@localhost>]

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Hello,

On May 21, 2009, at 9:24 AM, matthew sporleder wrote:

> Hi, I'm trying to write a pseudo device with an envsys component.  I
> mostly followed http://www.netbsd.org/docs/kernel/pseudo/ and got a
> working device, but now I get a panic when I attempt to do:
> sc->sc_sme = sysmon_envsys_create();
>
> My best guess is that I didn't get any memory allocated for my _softc
> structure, but I'm not really sure how to validate that.
>
> A rough cut of my code is here:
> http://mspo.com/code/screenblankenv.c.txt
>
> Can anyone offer some hints?  I'm a little stuck.

You use CFATTACH_DECL_NEW yet all your device methods use struct  
device * and there's a struct device in your softc. CFATTACH_DECL_NEW  
is for devices that split device and softc and use device_t instead.  
So, you panic because your code assumes that device and softc are the  
same thing but in reality you have only a device_t, try to access the  
softc fields behind it and segfault. To get your softc you need to  
call device_private() and store it in your softc for future reference.

have fun
Michael

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