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Re: [Qemu-block] blockdev-commit design
From: |
Kashyap Chamarthy |
Subject: |
Re: [Qemu-block] blockdev-commit design |
Date: |
Mon, 2 Oct 2017 17:01:27 +0200 |
User-agent: |
Mutt/1.6.0.1 (2016-04-01) |
On Tue, Sep 26, 2017 at 07:59:42PM +0200, Kevin Wolf wrote:
[...]
> In comparison with the old command, the important changes are:
>
> * top/base are node names instead of file names.
>
> * You don't need to specify the active layer any more (not the least
> because there could very well be more than one of them), but top
> becomes mandatory instead.
As a user of 'block-commit', I'm a bit confused on your above point.
Two questions:
(1) During active block commit, isn't "active layer" == "top"?
With the existing QMP `block-commit`, given:
A <- B <- C <- D (active)
To merge B, C, and D (the active layer) into A, I _have_ to specify
the active layer, which is "D", as a 'top' parameter:
{
"execute": "block-commit",
"arguments": {
"device": "node-D",
"job-id": "job0",
"top": "d.qcow2",
"base": "a.qcow2"
}
}
So when merging the top-most layer (D), there's at least one
scenario where we _are_ specifying the "active layer". And 'top'
_is_ mandatory as seen above.
So I wonder if I'm misinterpreting your wording.
(2) Also, just for my own education, can you mind expanding a bit more
about the "there can be more than one active layer" scenario?
Thanks.
[...]
--
/kashyap
- Re: [Qemu-block] blockdev-commit design,
Kashyap Chamarthy <=