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Bug 769144 - The parameter "to=<port>" of vnc works bad
Summary: The parameter "to=<port>" of vnc works bad
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm
Version: 7.0
Hardware: x86_64
OS: Linux
low
low
Target Milestone: rc
: 7.0
Assignee: Gerd Hoffmann
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-12-20 03:51 UTC by Sibiao Luo
Modified: 2013-12-12 08:19 UTC (History)
13 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2013-12-12 08:19:31 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Sibiao Luo 2011-12-20 03:51:32 UTC 
Description of problem:
The command line parameter value of "to=<port>" should specify the display range and the qemu will try to find a free one, The parameter "to=<port>" of vnc works bad when all the ports were in used.

Version-Release number of selected component (if applicable):
Server info:
2.6.32-220.el6.x86_64
qemu-kvm-0.12.1.2-2.210.el6.x86_64
tigervnc-1.0.90-0.17.20110314svn4359.el6.x86_64

Client info:
vnc-reflector-1.2.4-7.fc12.x86_64

How reproducible:
100%

Steps to Reproduce:
1. specified the display range in host A.
eg. ...-vnc :1,to=2 
2. take all the display number in used in host A.
eg. # /usr/libexec/qemu-kvm -vnc :1
    # /usr/libexec/qemu-kvm -vnc :2
3. start a guest  with the CLI of the step 1.
4. 'info vnc' in monitor shows the display actually used.
(qemu) info vnc
Server:
     address: 0.0.0.0:5903
        auth: none

Actual results:
the port number 5903 can be used.

Expected results:
the available port should be 5901,5902. for 5903 port, can not be used.

Additional info:
Comment 2 Gerd Hoffmann 2012-01-04 12:05:53 UTC 
Simple off-by-one bug, qemu stops checking at 5903 instead of 5902.
Comment 3 Ademar Reis 2012-03-22 17:49:00 UTC 
Simple bug, but low impact, apparently not even triggered by libvirt standard usage. Moving to 6.4.
Comment 8 Gerd Hoffmann 2013-12-11 16:48:04 UTC 
Please retest with latest qemu-kvm.
Comment 9 juzhang 2013-12-12 02:22:53 UTC 
Hi Sluo,

Could you have a try then update the result in the bz?

Best Regards,
Junyi
Comment 10 Sibiao Luo 2013-12-12 02:46:40 UTC 
(In reply to Gerd Hoffmann from comment #8)
> Please retest with latest qemu-kvm.
The rhel7.0 latest qemu-kvm did not hit this issue any more.
# /usr/libexec/qemu-kvm -vnc :1 &
# /usr/libexec/qemu-kvm -vnc :2 &
# /usr/libexec/qemu-kvm -vnc :1,to=2 -monitor stdio
QEMU 1.5.3 monitor - type 'help' for more information
(qemu) qemu-kvm: Failed to start VNC server on `:1,to=2': Failed to bind socket: Address already in use

host info:
# uname -r && rpm -q qemu-kvm-rhev && rpm -q seabios
3.10.0-60.el7.x86_64
qemu-kvm-rhev-1.5.3-21.el7.x86_64
seabios-1.7.2.2-4.el7.x86_64

Also tried the rhel6.5 host also not hit it any more.
# /usr/libexec/qemu-kvm -vnc :2 &
[1] 18092
# /usr/libexec/qemu-kvm -vnc :3 &
[2] 18098
# /usr/libexec/qemu-kvm -vnc :2,to=3 -monitor stdio
qemu-kvm: Failed to start VNC server on `:2,to=3': socket bind failed: Address already in use
host info:
# uname -r && rpm -q qemu-kvm-rhev
2.6.32-425.el6.x86_64
qemu-kvm-rhev-0.12.1.2-2.415.el6.x86_64

Best Regards,
sluo
Comment 11 Gerd Hoffmann 2013-12-12 08:19:31 UTC 
Good.  chardev hotplug backport also brought in some socket code patches, they probably fixed this one as side effect in rhel6.
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