disk_create and cdevsw_add

[Sam]

On Wed, 1 Sep 2004, Brian Fundakowski Feldman wrote:

> On Wed, Sep 01, 2004 at 12:32:58PM -0500, Sam wrote:
>> 'lo again,
>>
>> kern/subr_disk.c:/^disk_create/ takes
>> two cdevsw types, and I only vaguely
>> understand why.  Can someone explain it to me?
>>
>> I'm generally confused about resolving
>> entry points into the driver.  Does a
>> block device only get an open() after
>> registering it with disk_create?
>> Supposing I want to set some ioctls for
>> an aoecontrol utility (show all devices
>> known, eg), what would aoecontrol open
>> to ioctl?
>
> Create /dev/aoectl which exists only to do global aoe things; alternately,
> you could use a sysctl interface, but that's not really as clean.

I presume this means I should do a make_dev with a minor of 0
on module load as I see is recommended in DEV_MODULE(9).  Should
I then assume that unit 0 is this control file and be prepared
to fail any strategy calls to it?