Ballot Details: Resolve VIRTIO-137: used len field requirements not documented clearly (CLOSED)

Ballot Question Should the TC accept changes listed in the description to resolve issue VIRTIO-137, for inclusion in specification version(s) "virtio 1.0 cs03", and future versions of the specification?
Ballot Description Please vote Yes if you agree with all of the following.
If you disagree, please vote No.
If you don't have an opinion, please vote Abstain.

I move that:
The TC agrees to resolve the following specification issue:
VIRTIO-137: used len field requirements not documented clearly
When debugging qemu (which gets this wrong), I noted that the used ring's len field is only documented as follows:

field{len} the total of bytes written into the buffer.

Followed by a (presumably non-normative) note:
... is extremely useful for drivers using untrusted buffers: if you do not know exactly how much has been written by the device, you usually have to zero the buffer to ensure no data leakage occurs.

There is thus an implication that 'len' indicates the amount which was definitely overwritten by the device, but it should be clearly spelled out (such as what happens in the error case where the device may not know how much was actually overwritten).


The TC accepts the following proposed changes to the specification:

The TC agrees to include the above change(s) in specification version(s) "virtio 1.0 cs03", and future versions of the


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Ballot Options
VOTING CLOSED: Wednesday, 1 April 2015 @ 11:45 am EDT
Yes 8 100
No 0 0
Abstain 0
Open Date Wednesday, 25 March 2015 @ 11:45 am EDT
Close Date Wednesday, 1 April 2015 @ 11:45 am EDT
Ballot Type Official, as defined by organization policies and procedures

Voting Statistics

Number of votes cast (excluding abstentions) 8
Eligible members who have voted 8 of 10 80%
Eligible members who have not voted 2 of 10 20%

Voting Summary by Option

Options with highest number of votes are bold
Option # Votes % of Total
Yes 8 100%
No 0 0%
Abstain 0

Voting Details

Voter Name Company Vote * Time (UTC) Comments
* Bottomley, James Parallels IP Holdings GmbH Yes 2015-03-31 15:00:00
* Huck, Cornelia IBM Yes 2015-03-25 18:02:00
* Kiper, Daniel Oracle Yes 2015-03-26 14:53:00
* Moll, Pawel ARM Limited Yes 2015-03-25 17:09:00
* Russell, Rusty IBM Yes 2015-03-26 00:40:00
* Shah, Amit Red Hat Yes 2015-03-27 13:05:00
* Tsirkin, Michael Red Hat Yes 2015-03-25 17:10:00
* Venteicher, Bryan NetApp Yes 2015-03-29 19:24:00
* Mundt, Paul Huawei Technologies Co., Ltd. --
* Sohn, Richard Alcatel-Lucent --