Bug 1467797
| Summary: | [virtio-win][netkvm] guest mtu in device manager is not same as host_mtu | ||||||
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| Product: | Red Hat Enterprise Linux 7 | Reporter: | lijin <lijin> | ||||
| Component: | virtio-win | Assignee: | Yvugenfi <yvugenfi> | ||||
| virtio-win sub component: | virtio-win-prewhql | QA Contact: | Virtualization Bugs <virt-bugs> | ||||
| Status: | CLOSED WONTFIX | Docs Contact: | |||||
| Severity: | medium | ||||||
| Priority: | medium | CC: | ailan | ||||
| Version: | 7.4 | ||||||
| Target Milestone: | rc | ||||||
| Target Release: | --- | ||||||
| Hardware: | Unspecified | ||||||
| OS: | Unspecified | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2017-07-06 12:10:08 UTC | Type: | Bug | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Attachments: |
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This is by design. We cannot fix or change dynamically the MTU setting in Windows. According to new addition in virtio spec we will read host configuration and negotiate MTU using guest settings. |
Created attachment 1294485 [details] screenshot of mtu in guest Description of problem: Version-Release number of selected component (if applicable): virtio-win-prewhql How reproducible: 100% Steps to Reproduce: 1.boot guest with virtio-net-pci and set host_mtu=4000: /usr/libexec/qemu-kvm \ -M pc \ -cpu host \ -enable-kvm \ -m 2G \ -smp 4,cores=4 \ -nodefconfig \ -rtc base=localtime,driftfix=slew \ -drive file=win2008-64-iso.qcow2,if=none,serial=virtioblk1,format=qcow2,cache=none,werror=stop,rerror=stop,id=drive-virtio-disk0,aio=native \ -device ide-drive,drive=drive-virtio-disk0,id=virtio-disk0 \ -device piix3-usb-uhci,id=usb \ -device usb-tablet,id=tablet0 \ -k en-us \ -qmp tcp:0:4444,server,nowait \ -boot menu=on \ -monitor stdio \ -cdrom en_windows_server_2008_datacenter_enterprise_standard_sp2_x64_dvd_342336.iso \ -fda virtio-win-prewhql-0.1-140_amd64.vfd \ -drive file=virtio-win-prewhql-0.1-140.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 \ -vnc 0.0.0.0:1 -vga std \ -netdev tap,id=hostnet1,script=/etc/qemu-ifup,vhost=on -device virtio-net-pci,host_mtu=4000,netdev=hostnet1,mac=4e:63:28:bc:b1:01,id=net1 2.check guest mtu in cmd: # netsh interface ipv4 show subinterfaces 3.check guest mtu in device manager: device manger -> Red Hat VirtIO Ethernet Adapter -> advanced -> Init.MTUsize Actual results: after step2,guest mtu is 4000 as expected. MTU MediaSenseState Bytes In Bytes Out Interface ------ --------------- --------- --------- ------------- 4294967295 1 0 0 Loopback Pseudo-Interface 1 4000 1 18556 16682 Local Area Connection after step3,guest mtu in device manager is 1500,not 4000 Expected results: after step3,guest mtu in device manager should be same as host_mtu Additional info: