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Re: [Qemu-devel] [PATCH 02/21] qcow2: Add refcount_width to format-speci
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 02/21] qcow2: Add refcount_width to format-specific info |
Date: |
Tue, 11 Nov 2014 08:49:23 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 11/11/2014 01:11 AM, Max Reitz wrote:
>>> + .compat = g_strdup("0.10"),
>>> + .refcount_width = s->refcount_bits,
>> Hmm - is it really worth displaying a constant? Since the 0.10 format
>> cannot change the width from 16, I'm not sure if it adds anything to the
>> output to display it. After all, there's other things we omit for the
>> old format when they cannot be altered (such as the state of a lazy
>> flag). On the other hand, if it makes your changes to later iotests
>> easier for tests that operate on both image formats, I'm not opposed
>> to it.
>
> Yes, I thought about not displaying it. But whereas "corrupt" or "lazy
> refcounts" simply do not make sense with compat=0.10 images (it's simply
> impossible), the refcount width does make sense. It's always 16 bits
> (I'm noticing myself how I keep swapping between "bit" and "bits", but I
> just can't help it) but I personally find it interesting enough to
> display. I'd be fine with dropping it from compat=0.10, though.
>
> But in retrospect, I'd rather make the other two flags always visible
> than now drop this entry. However, not displaying a bool if it's always
> false makes more sense to me than not displaying an integer because it's
> always constant.
>
>> If you can make a strong argument for always outputting the constant
>> width of 16 for 0.10 formats, then I can live with it, so:
>
> You decide whether it's strong enough. :-)
>
> My main argument is "If a bool is not displayed one can assume it to be
> false; if an integer is not displayed which naturally cannot be 0, I
> will have no idea what it would be, even if it's constant for that image
> version".
Sounds fairly convincing :) Add a paragraph like that to the commit
message, and I'm sold!
>
>> Reviewed-by: Eric Blake <address@hidden>
So looks like you get to keep this.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, (continued)
- [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Max Reitz, 2014/11/10
- Re: [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Eric Blake, 2014/11/10
- Re: [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Max Reitz, 2014/11/11
- Re: [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Kevin Wolf, 2014/11/11
- Re: [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Max Reitz, 2014/11/11
- Re: [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Max Reitz, 2014/11/11
- Re: [Qemu-devel] [PATCH 03/21] qcow2: Use 64 bits for refcount values, Kevin Wolf, 2014/11/11
[Qemu-devel] [PATCH 02/21] qcow2: Add refcount_width to format-specific info, Max Reitz, 2014/11/10
[Qemu-devel] [PATCH 04/21] qcow2: Respect error in qcow2_alloc_bytes(), Max Reitz, 2014/11/10
[Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Max Reitz, 2014/11/10
- Re: [Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Eric Blake, 2014/11/10
- Re: [Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Max Reitz, 2014/11/11
- Re: [Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Eric Blake, 2014/11/11
- Re: [Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Max Reitz, 2014/11/11
- Re: [Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Eric Blake, 2014/11/11
- Re: [Qemu-devel] [PATCH 05/21] qcow2: Refcount overflow and qcow2_alloc_bytes(), Max Reitz, 2014/11/12
[Qemu-devel] [PATCH 07/21] qcow2: Helper for refcount array size calculation, Max Reitz, 2014/11/10