site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=0OKU+TNDTgJufdgiwYyh+6t6Omf6pzMzCOEVhDobMpM=; b=rEAByqCJ8kQlbQc4EX7lij8ieqpWJwA5059GLbpefRN7QKsvMHRONw+rlIFTMOBQNO0u3VEOe1xEsZWFDtX5EUOBS/nlMt2jnhRwGJA0UBvJADzKrtQA11eLOZuuszBeowefQkBKNa33S80zjdaxgoiXUyxC0DL7yvFfeBQ3bCM= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=QKdG9TQeOn8B1tkgd8F+grd22S2jPi8Q5ZczNZdCO3IFqmKVlOPYlxmaWBsOWmsPnTBgtangW3RbKoZRkJBO0rFS4O/cDCWHYBPhm0+oSII/oOyN4LFdbyCho4YwDNHcSohVBMYSCM7F4efA8d6kM3+E4s7hNaudJp71I724HL8= Rob, Thanks, a piece of code would be useful. Can you explain briefly how the stack should look like? If I subclass IOBlockStorageDevice to which nub should I attach the newly created driver? Regards, V. On Thu, Feb 21, 2008 at 10:02 PM, Rob McKeever <robm@apple.com> wrote:

Valentin,

If I understand what you're trying to do, I don't think you need to recreate the entire stack. You should be able to subclass IOBlockStorageDevice and give it whatever backing store you want.

I can provide you with some code that shows how to do this if you need.

-Rob

-- Rob McKeever, robm@apple.com Mass Storage Group, CPU Software Engineering Apple Computer

On Feb 21, 2008, at 5:47 AM, Valentin Slavov wrote:

...

Hello

I need to develop a virtual block device which will be used for testing filesystem operations with files larger than 16TB or so. Obviously all this space should be virtual (in a sparse image sense), however there should be some kind of backing store to hold the filesystem meta data. Since meta data is written at different places in the volume (hfs+ keeps a backup at the end of the device and so on, a backing store for certain "ranges" should be used. The backing stores should be configurable (I was thinking of providing bsd names and searching the I/O Kit registry for IOMedia objects, and attaching them to my driver). Another solution would be to implement the driver as a filter scheme but this is inflexible since backing store cannot be configured easily.

Although the first solution seems more appropriate, I need to implement a whole driver stack for virtual devices (like the apple disk image drivers), but unfortunately I can't find sufficient documentation for this task. I'd like to know if there are more appropriate solutions and other hints that might be useful.

Thanks in advance V. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/robm%40apple.com

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