Re: [ANNOUNCE] block device interfaces changes

[Alan Cox]

> [User mode interface]
> int devicecontrol(int filehandle, unsigned command,
>                   size_t insize, void *inbuf,
>                   size_t outsize, void *outbuf);
> 
> That is, the parameters clearly indicate which access is allowed to what  
> memory, and how big buffers are. The old ioctl() interface could translate  

This wouldn't be flexible enough. Many ioctls pass multiple objects around.
For the standard form the existing ioctls encode their size. Also since the
copy*user* stuff does inbuilt fault handling and we need to know the object
size for the copy it has no code size improvement

devicecontrol in the form you give has no value outside a message passing
microkernel.