On 08/26/2015 06:01 PM, Jeff Cody wrote: > On Wed, Aug 26, 2015 at 02:17:17PM -0400, Programmingkid wrote: >> >> On Aug 26, 2015, at 2:08 PM, Jeff Cody wrote: >> >>> On Wed, Aug 26, 2015 at 01:29:04PM -0400, Programmingkid wrote: >>>> >>>> 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 <programmingk...@gmail.com> 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. >>> >>> IMO, the number of characters to type is pretty low on the list of >>> requirements, although it can still be addressed secondary to other >>> concerns. >>> >>> I should have made this in reply to Markus' other email, because the >>> important part of this is try and address his point #2: >>> >>> (from Markus' other email): >>>> 2. The ID must be well-formed. >>> >>> To have a well-formed ID, we need to have know requirements of the ID >>> structure (i.e. the why and what of it all) >>> >>> I don't know if the three requirements I had above apply to all areas >>> in QEMU, but I expect they do, in varying degrees of importance. The >>> length itself can be tweaked. >>> >>> Talking with John Snow over IRC (added to the CC), one thing he >>> suggested was adding in sub-domain spaces; e.g.: >>> >>> __qemu#bn#00000000#IAIYNXXR >>> >>> Where the 'bn' in this case would be for Block Nodes, etc.. >>> >>> This may make the scheme extensible through QEMU, where auto-generated >>> IDs are desired. >>> >>> (sorry to say, this lengthens things, rather than shortening them!) >>> >>> We can, of course, make the string shorter - if the random characters >>> are just there for spoiling predictability, then 2-3 should be >>> sufficient. We could then end up with something like this: >>> >>> __qemu#bn#00000000#XR >>> >>> The "__qemu" part of the namespace could be shortened as well, but it >>> would be nice if it was easy recognizable as being from QEMU. >> >> If this ID format was supported, I'm thinking being able to copy and paste >> from >> the monitor is a necessary feature. >> >> Any way it could be shorted? I was hoping no more than three characters >> long. >> > > Likely could be shorter, but something in the realm of three > characters doesn't seem very realistic. > >> If this were the format of the ID, maybe we could put the value in a table >> that >> would translate this long ID to a shorter version. Or maybe a mathematical >> function >> could be applied to the value to give it some user-friendly value. > > I'm afraid this would discard pretty much all the benefits of the ID > generation scheme.
At this point, why not specify a user-friendly ID yourself? If there is some technical reason you cannot, maybe we should fix the interface to allow you to do so. Auto-generated IDs are not likely to be short, pretty, or easy to type due to the constraints Jeff Cody laid out earlier. > >> >> I do think your idea virtually eliminates the problem of ID collisions.
