Bug 625333
| Summary: | qemu treatment of -nodefconfig and -readconfig problematic for debug | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | john cooper <john.cooper> | ||||
| Component: | qemu-kvm | Assignee: | john cooper <john.cooper> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 6.0 | CC: | amit.shah, lihuang, michen, mkenneth, nobody, shuang, tburke, virt-maint | ||||
| Target Milestone: | beta | ||||||
| Target Release: | --- | ||||||
| Hardware: | All | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | qemu-kvm-0.12.1.2-2.135.el6 | Doc Type: | Bug Fix | ||||
| Doc Text: |
Cause
Currently -nodefconfig doesn't disable import of cpu-x86_64.conf.
This combined with -readconfig imports occurring after cpudef_setup()
disallow pointing qemu at an alternate cpu-x86_64.conf file.
Consequence
User effectively can't read in alternate cpu-x86_64.conf file impacting
qemu debug and potentially end user local configuration.
Workaround
Requires moving/overwriting default config files by the user.
Result
-nodefconfig works as intended and intuitively expected.
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Story Points: | --- | ||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2011-05-19 11:29:12 UTC | Type: | --- | ||||
| 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: | 580953 | ||||||
| Attachments: |
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Remove "sse4a, abm, svm" from cpu64-rhel6 extfeature_ecx in my-cpu-x86_64.conf config file. boot guest with -nodefconfig -readconfig ? -readconfig my-cpu-x86_64.conf -cpu cpu64-rhel6,check on host lack "sse4a, abm, svm" Result: fix on qemu-kvm-0.12.1.2-2.145.el6.x86_64 1. qemu-kvm-0.12.1.2-2.132.el6.x86_64 [root@amd-4450b-4-2 ~]# /usr/libexec/qemu-kvm -nodefconfig -readconfig ? -readconfig my-cpu-x86_64.conf -cpu cpu64-rhel6,check parsed config file /usr/share/qemu-kvm/cpu-model/cpu-x86_64.conf parsed config file /root/cpu-x86_64.conf warning: host cpuid 8000_0001:ecx flag restricted to guest 'svm' [0x00000004] warning: host cpuid 8000_0001:ecx lacks requested flag 'abm' [0x00000020] warning: host cpuid 8000_0001:ecx lacks requested flag 'sse4a' [0x00000040] 2. qemu-kvm-0.12.1.2-2.145.el6.x86_64 1). /usr/libexec/qemu-kvm -nodefconfig -readconfig ? -readconfig my-cpu-x86_64.conf -cpu cpu64-rhel6,check parsed config file /usr/share/qemu-kvm/cpu-model/cpu-x86_64.conf parsed config file /root/cpu-x86_64.conf Using CPU model "cpu64-rhel6,check" 2). /usr/libexec/qemu-kvm -nodefconfig -readconfig ? -cpu cp4-rhel6,check parsed config file /usr/share/qemu-kvm/cpu-model/cpu-x86_64.conf Using CPU model "cpu64-rhel6,check" warning: host cpuid 8000_0001:ecx flag restricted to guest 'svm' [0x00000004] warning: host cpuid 8000_0001:ecx lacks requested flag 'abm' [0x00000020] warning: host cpuid 8000_0001:ecx lacks requested flag 'sse4a' [0x00000040] move to verified based on comment#8 Added CCFR
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New Contents:
Cause
Currently -nodefconfig doesn't disable import of cpu-x86_64.conf.
This combined with -readconfig imports occurring after cpudef_setup()
disallow pointing qemu at an alternate cpu-x86_64.conf file.
Consequence
User effectively can't read in alternate cpu-x86_64.conf file impacting
qemu debug and potentially end user local configuration.
Workaround
Requires moving/overwriting default config files by the user.
Result
-nodefconfig works as intended and intuitively expected.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2011-0534.html An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2011-0534.html |
Created attachment 439585 [details] Example patch providing above fix. Description of problem: Currently -nodefconfig doesn't disable import of cpu-x86_64.conf. This combined with -readconfig imports occurring after cpudef_setup() disallow pointing qemu at an alternate cpu-x86_64.conf file. Notably, -readconfig support is broken. Version-Release number of selected component (if applicable): RHEL6.0-20100816.n.0-Server-x86_64 How reproducible: launch qemu with: -nodefconfig -readconfig ? -readconfig mydebug/cpu-x86_64.conf the definitions in the system installed: /usr/share/qemu-kvm/cpu-model/cpu-x86_64.conf are unconditionally imported while the: mydebug/cpu-x86_64.conf definitions are read in but have no effect due to occurring after the call to cpudef_setup() in the above example. Steps to Reproduce: (as stated above) Actual results: can't read in alternate cpu-x86_64.conf file. Expected results: should be able to use CLI as described above for debug. Additional info: 1. Broken -readconfig support went unnoticed as libvirt does not use this option. Given libvirt dependencies it may be necessary to entertain another flag to disable import of cpu-x86_64.conf as libvirt assumes this file is unconditionally imported. 2. A patch is attached which includes import of cpu-x86_64.conf under -nodefconfig and fixes the behavior of -readconfig. 3. All of the above and related cpu config logic is subject to change pending reconciling this rhel6 special functionality upstream.