Re: Passing ioctls between front-end and back-end drivers

[Nick Logan <nick_logan@symantec.com>]

Ah, that explains why I couldn't find out how to do it. The ioctl's that 
I am thinking of are vendor specific. I'm looking at supporting devices 
in Dom0 that can be accessed from the guest domains and part of the 
driver functionality requires ioctls to get/set attributes etc. It would 
be up to the backend to determine if the ioctls were valid or not. I 
agree that this is rather Linux/Unix specific but in my case it's a 
fundamental part of the driver.

Maybe some of the attributes can be passed via Xenstore, I'll investigate.

Nick

 Ian Pratt wrote:

>>I see that the block driver supports requests for READ, WRITE 
>>and PROBE. 
>>Is there any recommended way to pass ioctl requests from the 
>>front-end to be executed by the back-end driver?
>>    
>>
>
>Currently, no.
>
>Creating a new request operation type that allows the front end to pass
>through ioctls would be useful, but it ends up being rather Linux
>specific. Further, for security reasons the backend is going to need to
>be able to decode the ioctl and decide whether its safe to issue or not.
>It would be better to have a 'wire protocol' for this.
>
>A mechanism for passing scsi commands through would be better, but even
>then there are a bunch of vendor-specific ones its not entirely easy to
>tell whether they should be allowed by a guest or not. I suspect we need
>to draw up a list of what "ioctls" should be allowed. What one do you
>want to perform?
>
>Ian 
>  
>