Bug 1352808
Summary: | [Q35] Fail to assign [mem size 0x01000000 64bit pref] when hot-plug virtio block device | ||||||
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Product: | Red Hat Enterprise Linux 7 | Reporter: | jingzhao <jinzhao> | ||||
Component: | qemu-kvm-rhev | Assignee: | Marcel Apfelbaum <marcel> | ||||
Status: | CLOSED NOTABUG | QA Contact: | Virtualization Bugs <virt-bugs> | ||||
Severity: | high | Docs Contact: | |||||
Priority: | high | ||||||
Version: | 7.3 | CC: | chayang, juzhang, knoel, marcel, virt-maint, yama, yanghliu, yduan, yiwei | ||||
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: | 2016-08-08 11:29:44 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: | |||||||
Bug Depends On: | |||||||
Bug Blocks: | 1288337 | ||||||
Attachments: |
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Description
jingzhao
2016-07-05 06:53:43 UTC
Created attachment 1176264 [details]
dmesg log
Hi, This is actually not a problem. The error messages from dmesg result from the fact the firmware may assign less MMIO space than virtio-1 devices need. The virtio 1.0 devices need 8MB space while SeaBIOS (for example) reserves only 2MB. Some guests, Linux for example, will try to re-balance the PCI root bus MMIO space and assign to pci-bridges/pcie-ports more memory space. Sometimes the guest OS will succeed and sometimes not. The example you presented is actually a good one with a happy ending. The device runs OK, right? Try the same with a i440fx machine and a pci-bridge while requesting virtio-1 mode and the Linux (on guest) will not even try to re-balance. Again, the root-cause is virtio-1 mode that requests more MMIO space than reserved by the firmware. What I will take for this BZ is we need to see what to do about this discrepancy. Thanks, Marcel *** Bug 1353141 has been marked as a duplicate of this bug. *** *** Bug 1355661 has been marked as a duplicate of this bug. *** *** Bug 1245125 has been marked as a duplicate of this bug. *** I have decided to open BZ 1365613 to track the root cause of this BZ. Thanks, Marcel |