1. Things like "CMPXCHG16B", PAE/NX might just become "hidden" VM settings. Same as Firmware = BIOS or EFI. (not even needed in GUI, but setting "Windows 8" should automatically enable them).
2. My patch doesn't delete "OS type" information from *.vbox files, until user actually changes any VM settings for a particular VM. 3. When he re-upgrades to new VirtualBox, he can manually choose the right OS type (Windows 8 or 10). 4. This is way better than having inaccessible VMs. 5. Why "CMPXCHG16B", "NX/PAE" and other such instructions are not enabled by default ? On Fri, May 8, 2015 at 3:44 PM, Klaus Espenlaub <[email protected]> wrote: > Hi Alexey, > > On 08.05.2015 00:08, Alexey Eromenko wrote: >> Hi, >> >> Today if I revert to older VirtualBox (to 4.3.20) from newer (v5.0 >> BETA), I lose access to certain VMs, such as "Windows 10", because it >> has a new guest OS type ID. >> >> Those VMs become "inaccessible" for no good reason. I can understand a >> VM becoming "inaccessible" if hard disk new format is coming or a disk >> image is lacking, but Guest OS type ? > > Yes, it's intentional. The reason is that VirtualBox uses it for certain > small detail "tweaks" - like for Windows 8.1 it enables the CMPXCHG16B > instruction support. > >> My patch allows to recognize and start VMs with future guest OS type >> IDs. They will revert to "unknown" OS type. > > See above. Possible loss of significant information, which might make > some VMs fail to run in the new version after upgrading again. That's > why we opted for making the VMs inaccessible. > > We're running into such issues ourselves, and we keep re-evaluating out > options, but so far we decided that the risk outweighs the benefits of > being more generous with new configs in old versions. > > Another way to look at it: predicting the effects of such "config > adjustments" would need a time machine: this code needs to be in the > "old" version, which means that it would be a promise that we will never > change the underlying assumption. > >> This is particularly useful in combination with "vbox-unattended" >> patch, that adds new OS types every now and then, but also for Oracle >> VirtualBox itself. >> >> I have tested it together with VirtualBox GUI and with VBoxManage commands. >> Plus tested OVF, Import / Export appliance. > > Klaus > > _______________________________________________ > vbox-dev mailing list > [email protected] > https://www.virtualbox.org/mailman/listinfo/vbox-dev -- -Alexey Eromenko "Technologov" _______________________________________________ vbox-dev mailing list [email protected] https://www.virtualbox.org/mailman/listinfo/vbox-dev
