Re: User space interface to controller.

Subject: Re: User space interface to controller.

From: Chris Sarcone <email@hidden>

Date: Mon, 26 Sep 2005 16:51:21 -0700

Delivered-to: email@hidden

Tom --

I have an ATA RAID HBA which is managed by a driver which is a subclass of IOSCSIParallelInterfaceController.

I need to provide an interface for my user space tools to manage the RAID controller. Under Linux, FreeBSD and

Windows this is accomplished via an ioctl interface to the RAID controller driver. The largest ioctl payloads are 8K.

You can create a custom subclass of IOUserClient. Since the payload could be larger than 4K, you can't simply use IOConnectMethodStructIStructO. You will have to save the task_t for the calling process (override initWithTask() and save the task_t) and you'll have to wrap the address of the user-space buffer with an IOMemoryDescriptor using withAddress() and passing the task_t. Once you do that, you prepare() the buffer, then you can DMA with it, call readBytes() or writeBytes(), etc. When done, call complete() on it, then release() it.

HTH,

-- Chris

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References:
	>RE: User space interface to controller. (From: "Tom Couch" <email@hidden>)