[yocto] Autoload kernel module works only once

[Leonardo Sandoval]

On Mon, 2017-03-13 at 14:36 +0000, Andrea Laini wrote:
> Hi everybody,
> 
>  
> 
> I’m getting some errors after building my Linux distro with the use of
> KERNEL_MODULE_AUTOLOAD to allow autoloading 2 of my custom out-of-tree
> device at boot time. We’ve a Poky 1.7 version.
> 
>  
> 
> So, before building the new image with the Yocto keyword
> KERNEL_MODULE_AUTOLOAD, I was able to load and open (and, obviously,
> use) my devices simply by calling ‘modprobe mydevice’ after logging
> in. Restarting the board, everything was still working well.
> 
> Since I’ve rebuild a new image enabling module autoload at boot time,
> modules are always loaded, but I’m able to open (and use) them only
> really first time I switched on the board after downloading new image.
> After the first reboot, LKMs are still loaded (calling ‘lsmod’ show
> them) but I can’t open them, neither from my C program nor
> reading/writing them from ‘/dev/mydevice’.


I am not a kernel expert, but do you know if file permissions change
after first boot? you may enable debugging at your device and view it
with dmesg, that would give you more clues. 

> 
>  
> 
> To me it sound a very strange behavior.
> 
>  
> 
> Hope anyone can help,
> 
> Many thanks
> 
>  
> 
> Andrea
> 
>  
> 
> 
> Andrea Laini
> 
> Email:andrea.laini at claypaky.it
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