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Bug 1363618 - When set disable-legacy=on and disable-modern=on,guest can't recognise this device.
Summary: When set disable-legacy=on and disable-modern=on,guest can't recognise this d...
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm-rhev
Version: 7.3
Hardware: x86_64
OS: Linux
Target Milestone: rc
: ---
Assignee: jason wang
QA Contact: Virtualization Bugs
Depends On:
TreeView+ depends on / blocked
Reported: 2016-08-03 08:18 UTC by weliao
Modified: 2016-08-23 07:18 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2016-08-23 07:18:13 UTC
Target Upstream Version:

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Description weliao 2016-08-03 08:18:28 UTC
Description of problem:
Launch a NIC with virtio1.0, then hot unplug this NIC, and hotplug a virtio0.95 NIC,guest can't recognise this device.

Version-Release number of selected component (if applicable):
How reproducible:

Steps to Reproduce:
1.Launch a Guest with virtio1.0 
-netdev tap,id=hostnet0,vhost=on,poll-us=3,vhost=off,queues=4   \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:01:ee:66:23,bus=pci.0,addr=0x4,disable-legacy=off,disable-modern=off,vectors=10,mq=on unplug this device.
(qemu) device_del net0 plug a virtio0.95 device
(qemu)device_add virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:01:ee:66:23,bus=pci.0,addr=0x4,disable-legacy=on,disable-modern=on,vectors=10

Actual results:
in guest: ip link show
guest can't recognise this device.

Expected results:
Guest can recognise this device.

Additional info:
/usr/libexec/qemu-kvm \
-name rhel7.3 -M pc \
-cpu SandyBridge \
-m 2048 -realtime mlock=off -nodefaults \
-smp 4 \
-device virtio-scsi-pci,id=scsi2,indirect_desc=off,event_idx=off,bus=pci.0,disable-legacy=off,disable-modern=off \
-drive file=/mnt/RHEL7_3.qcow2,if=none,id=drive-virtio-disk0,format=qcow2 \
-device scsi-hd,bus=scsi2.0,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1  \
-netdev tap,id=hostnet0,vhost=on,poll-us=3,vhost=off,queues=4   \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:01:ee:66:23,bus=pci.0,addr=0x4,disable-legacy=off,disable-modern=off,vectors=10,mq=on \
-vnc :1 -monitor stdio \
 -boot menu=on \
-qmp tcp:0:4446,server,nowait \
-vga cirrus

Comment 1 weliao 2016-08-03 09:50:28 UTC
Sorry, seem no relationship with virtio1.0 or virtio0.95, I retested it find because disable-legacy=on,disable-modern=on. when disable-legacy and disable-modern all set "on", will can't recognise the device.

Comment 3 Amnon Ilan 2016-08-08 16:05:36 UTC
This seems to make sense, when the device is not legacy and not modern it 
cannot communicate.. 
I guess the only problem is that there is no error message on that.
Jason, can you have a look?

Comment 4 jason wang 2016-08-23 07:18:13 UTC
Yes, I don't think disable-legacy=on,disable-modern=on can work. So close this first, feel free to reopen.

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