Re: [PATCH v10 10/26] gunyah: vm_mgr: Introduce basic VM Manager

[Alex Elder]

On 2/24/23 4:48 PM, Elliot Berman wrote:
> I'd be open to making GH_CREATE_VM take a struct argument today, but I 
> really don't know what size or what needs to be in that struct. My hope 
> is that we can get away with just an integer for future needs. If 
> integer doesn't suit, then new ioctl would need to be created. I think 
> there's same problem if I pick some struct today (the struct may not 
> suit tomorrow and we need to create new ioctl for the new struct).

I'd like someone to back me up (or tell me I'm wrong), but...

I think you can still pass a void in/out pointer, which can
be interpreted in an IOCTL-specific way, as long as it can
be unambiguously processed.

So if you passed a non-null pointer, what it referred to
could contain a key that defines the way to interpret it.

You can't take away a behavior you've once supported, but I
*think* you can add a new behavior (with a new structure
that identifies itself).

So if that is correct, you can extend a single IOCTL.  But
sadly I can't tell you I'm sure this is correct.

					-Alex