Re: [Qemu-devel] Should we auto-generate IDs?

[Programmingkid]

On Aug 26, 2015, at 1:25 PM, Jeff Cody wrote:

> On Wed, Aug 26, 2015 at 06:31:57PM +0200, Markus Armbruster wrote:
>> Did you drop cc's intentionally?  I put them right back.
>> 
>> Programmingkid <address@hidden> writes:
>> 
>>> On Aug 25, 2015, at 8:38 AM, Markus Armbruster wrote:
>>> 
>>>> You're proposing to revise a qdev design decision, namely the purpose of
>>>> IDs.  This has been discussed before, and IDs remained unchanged.
>>>> Perhaps it's time to revisit this issue.  Cc'ing a few more people.
>>>> 
>>>> Relevant prior threads:
>>>> * [PATCH] qdev: Reject duplicate and anti-social device IDs
>>>> http://thread.gmane.org/gmane.comp.emulators.qemu/71230/focus=72272
>>>> * [PATCH 6/6] qdev: Generate IDs for anonymous devices
>>>> http://thread.gmane.org/gmane.comp.emulators.qemu/114853/focus=114858
>>>> * [PATCH] qdev: Assign a default device ID when none is provided.
>>>> http://thread.gmane.org/gmane.comp.emulators.qemu/249702
>>>> * IDs in QOM (was: [PATCH] util: Emancipate id_wellformed() from QemuOpt
>>>> http://thread.gmane.org/gmane.comp.emulators.qemu/299945/focus=300381
>>>> 
>>> 
>>> After reading all the threads, I realize why all the attempts to
>>> accept a device ID patch failed.
>>> It is because it was assumed everyone would agree on one patch to
>>> accept. This is
>>> very unlikely. It would take someone in a leadership position to
>>> decide which patch
>>> should be accepted. From one of the threads above, I saw Anthony
>>> Liguori participate.
>>> He was in the perfect position to make the choice. The person who is
>>> in his position now
>>> is Peter Maydell. Maybe we should just ask him to look at all the
>>> candidate patches and
>>> have him pick one to use. 
>> 
>> Yes, when no consensus emerges, problems tend to go unsolved.
>> 
>> Before we appeal to authority to break the deadlock, we should make
>> another attempt at finding consensus.
>> 
>> I know that we've entertained the idea of automatically generated IDs
>> for block layer objects (that's why I cc'ed some block guys).
> 
> Yeah, I was one of the ones that proposed some auto-generated IDs for
> the block layer, specifically for BlockDriverState, making use of the
> node-name field that Benoit introduced a while ago.  Here is my patch
> (not sure if this is the latest version, but it is sufficient for this
> discussion):
> 
> http://patchwork.ozlabs.org/patch/355990/
> 
> I'm not sure about the requirements needed by device ID names, and
> they may of course differ from what I was thinking for BDS entries.
> 
> Here is what I was after with my patch for node-name auto-generation:
> 
> * Identifiable as QEMU generated / reserved namespace
> 
> * Guaranteed uniqueness
> 
> * Non-predictable (don't want users trying to guess / assume
>  generated node-names)
> 
> My approach was overkill in some ways (24 characters!).  But for
> better or worse, what I had was:
> 
>                __qemu##00000000IAIYNXXR
>                ^^^^^^^^
> QEMU namespace ----|    ^^^^^^^^
>                          |     ^^^^^^^^^
> Increment counter, unique |         |
>                                    |
> Random string, to spoil prediction  |

Yikes! 24 characters long. That is a bit much to type. Thank you very much
for your effort.