Re: [Xen-devel] feature request - prevent user stupidity (eg mine)

[Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>]

>> >The nice thing about the hotplug scripts is that they Just Work for
>> >dynamically adding devices.  Unless I've misread Kan's code, it won't
>> > catch a user accidentally adding a duplicate blkdev to a running domain,
>> > which is a shame.
>>
>> Could you teach me a blkdev definition or a adding blkdev operation that
>> my code cannot catch that you think of?  I'd like to test them by my code.
>
>I was thinking your code didn't get run at block-attach, but later on I 
>started to think maybe it was :-)  Is it? ;-)

I tested xm block-attach command by my patch.  I believe it's okay. 

# xm list --long vm1
(domain
<<snip>>
    (device
        (vbd
            (uname file:/xen/rhel4u2.root.img-vm1)
            (uuid 40221979-3528-afe0-a018-da8e4b956590)
            (mode w)
            (dev hda1:disk)
            (backend 0)
            (bootable 1)
        )
    )
<<snip>>
# xm block-attach vm1 file:/xen/rhel4u2.root.img-vm1 hdb1 w
Error: The uname "file:/xen/rhel4u2.root.img-vm1" is already defined
Usage: xm block-attach <Domain> <BackDev> <FrontDev> <Mode> [BackDomain]

Create a new virtual block device.

Best regards, 
 Kan


>> >We should try to figure out if this can be added reliably to the blkdev
>> >hotplug scripts.  If not, maybe we should put all the checking into Xend,
>> >with hooks to validate added devices.
>>
>> I'd like to check a duplicate blkdev for both xm new command and xm create
>> command, so that I added the checking into xend(XendConfig.py).
>> If the duplicate blkdev is notified of by xm start command, I think that
>> it is late.
>
>Ah, I hadn't thought about xm new.  Well, in that case it sounds fairly 
>reasonable to add to Xend, and your code looked OK to me.  Given that, I'd 
>have no objections to your patch going in.  Might save me from PBKAC (
>Problem 
>Between Keyboard And Chair) one day :-)
>
>Cheers,
>Mark
>
>-- 
>Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
>Mark: To answer a question with a question: What use is a skateboard?
>Dave: Skateboards have wheels.
>Mark: My wheel has a wheel!
>
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