Re: [Qemu-devel] Re: [PATCH 08/12] block: Catch attempt to attach multiple devices to a blockdev

[Kevin Wolf]

Am 28.06.2010 12:16, schrieb Christoph Hellwig:
> On Mon, Jun 28, 2010 at 10:24:49AM +0200, Kevin Wolf wrote:
>> How would breaking compatibility help us? For the user a USB MSD is only
>> one device, so requiring two -device parameters sounds wrong.
> 
> But it is separate devices.  At least the standards compliant usb
> storage devices just are a bride of scsi commands over usb and fit into
> the SAM device model, which makes a difference between initiator, target
> and LUN.  So having a different device for the specific target vs the
> initiator port makes a difference. (and yes, we're still totally missing
> support for multiple luns, which would require another level of
> devices).  Trying to hide this is not all that useful - not anymore
> useful than hiding it on a "normal" scsi host controller anyway.

Maybe we need something like composed devices? So when the user asks for
a USB stick, he actually gets all devices that this stick internally
uses? Otherwise it becomes really hard to use -device directly.

I guess the same applies for mainboards, CPUs and probably some more
things, though I don't really know how these are (planned to be) done in
qdev.

Kevin