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From: Markus Armbruster <armbru@redhat.com>
Subject: Re: [Qemu-devel] Re: RFC: blockdev_add & friends, brief rationale,
	QMP docs
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Date: Mon, 31 May 2010 13:05:37 +0200
In-Reply-To: <4C022BCB.5000907@redhat.com> (Avi Kivity's message of "Sun, 30
	May 2010 12:11:39 +0300")
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To: Avi Kivity <avi@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>, Luiz Capitulino <lcapitulino@redhat.com>

Avi Kivity <avi@redhat.com> writes:

> On 05/28/2010 10:24 PM, Luiz Capitulino wrote:
>>
>>> If a password is needed, we should throw an error and let the QMP client
>>> set the password and try again.
>>>      
>>   It's what we do today, a password should be set with block_passwd before
>> issuing the change command. Otherwise an error is throw.
>>    
>
> Is the password some kind of global or per-monitor property?  In that
> case it doesn't work with parallel execution of commands; better to
> have a password field (or assign IDs to passwords and require a
> passwordid=... argument).

It sets the password in the host BlockDriverState.  Which must already
exist, i.e. you do it after blockdev_add.

What happens if the guest device accesses the host drive before the key
is set?

Anything wrong with passing the password as argument?  Did we avoid that
to protect naive users from exposing their password via argv[]?  That
"argument" doesn't apply to QMP.