On Friday 07 March 2014 01:33:11 John A. Wallace wrote: > > 4.3.8 in general is a stable release but due to changes in certain > > aspects of machine status registers there might be problems with > > certain host CPUs. > > But again, without more information we can't help. > > Is there something specific you can point to for us to see which "certain > host CPUs" you have in mind? I would like to understand this problem > better, but without more information it is hard to see whether I can > possibly troubleshoot this issue or whether mine might be one of those > included among the group of certain host CPUs. If it is incompatible, that > is one thing; but if it is not, then, well, that would be something else.
In VirtualBox 4.3.8 the way how machine status registers are emulated was changed. VirtualBox up to version 4.3.6 used sensible default values for most MSRs. These values were determined by trial and error to make most guests happy. However, the set of MSRs depends on the CPU microarchitecture. For instance, Intel Pention M is very different from Intel Core i7. Certain guests or guest drivers expect different MSR behavior for different CPUs. To fulfil this expectation, the behavior was changed in 4.3.8. This change was actually planned for 4.3.0 but it wasn't ready in time. You get a first impression if you look at this directory: https://www.virtualbox.org/browser/vbox/trunk/src/VBox/VMM/VMMR3/cpus For most CPUs, the behavior shouldn't be much different but for CPUs which differ too much from all examples in this directory, the emulation is probably not precise enough. After 4.3.8 we added support for Intel SandyBridge as well as support for more recent AMD Athlon 64 X2 CPUs which should fix some problems users saw on these CPUs. We cannot provide a list of supported CPUs. Often the difference between the CPU microarchitectures is that small that one can use the complete emulation of the previous architecture. We have a number of different CPU architectures available and did extensive tests but we surely cannot catch all problems. Therefore it is important that users open tickets for such 4.3.8 regressions (actually it's very important to differ between 4.3.8 regressions and bugs users already saw with 4.3.6!) on our public bugtracker so we can investigate and provide 4.3.9 test builds so users can check if their problem is now fixed or not. For instance such reports: https://www.virtualbox.org/ticket/12734 https://www.virtualbox.org/ticket/12736 https://www.virtualbox.org/ticket/12744 And it is important for us to get the feedback if such problem is fixed! But as I said in a previews mail, the normal user should not experience any different behavior between 4.3.6 and 4.3.8. In general, the 4.3.8 release is quite stable. Kind regards, Frank -- Dr.-Ing. Frank Mehnert | Software Development Director, VirtualBox ORACLE Deutschland B.V. & Co. KG | Werkstr. 24 | 71384 Weinstadt, Germany Hauptverwaltung: Riesstr. 25, D-80992 München Registergericht: Amtsgericht München, HRA 95603 Geschäftsführer: Jürgen Kunz Komplementärin: ORACLE Deutschland Verwaltung B.V. Hertogswetering 163/167, 3543 AS Utrecht, Niederlande Handelsregister der Handelskammer Midden-Niederlande, Nr. 30143697 Geschäftsführer: Alexander van der Ven, Astrid Kepper, Val Maher
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