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From: Peter Lieven <pl@kamp.de>
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Date: Thu, 4 Jul 2013 23:10:56 +0200
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Subject: Re: [Qemu-devel] [PATCH 10/17] block: define get_block_status
	return value
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com


Am 04.07.2013 um 10:13 schrieb Paolo Bonzini <pbonzini@redhat.com>:

> Il 03/07/2013 23:04, Peter Lieven ha scritto:
>>>> Define the return value of get_block_status.  Bits 0, 1, 2 and 8-62
>>>> are valid; bit 63 (the sign bit) is reserved for errors.  Bits 3-7
>>>> are left for future extensions.
>> Is Bit 8 not also reserved for future use? BDRV_SECTOR_BITS is 9.
> 
> Right.
> 
>> Can you explain which information is exactly returned in Bits 9-62?
> 
> Bits 9-62 are the offset at which the data is stored in bs->file, they
> are valid if bit 2 (BDRV_BLOCK_OFFSET_VALID) is 1.

Ok, so this is if bs->file is not linear?

If we return the offset into bs->file this would only make sense if the data
at that position is raw and not encoded otherwise and if *pnum is limited
to the size of the extend at that position, right?

I currently do not understand for what operation this info is needed.

Maybe you could add some info to the commit or the function including
your comment from above.

Thanks,
Peter