Re: [Qemu-devel] Dropped CPU feature names and backward compatibility

[Paolo Bonzini]

On 18/09/2018 16:22, Eduardo Habkost wrote:
> On Tue, Sep 18, 2018 at 04:02:54PM +0200, Paolo Bonzini wrote:
>> On 18/09/2018 15:14, Eduardo Habkost wrote:
>>> If it broke something, we should restore the option names and
>>> declare them as deprecated.
>>
>> I think in this particular case it's okay to add them back as no-ops,
>> especially we'd actually want them to be customizable for user-mode
>> emulation.
> 
> We can make the flag work on user-mode emulation, but I wouldn't
> like to keep QEMU silent if the option was explicitly set in the
> command-line in system emulation, because it means the user or
> some software component is really confused and trying to do
> something that is never going to work.

They just want to copy the host flags blindly into the guest.  osxsave
and ospke require some collaboration from the guest OS, but it should be
pretty harmless to have them on the command line, because in the end the
apps _should_ anyway be checking OSPKE.  If somebody is writing such an
app and is puzzled that OSPKE is missing, they should first of all ask
themselves if they have installed the right guest OS.

Paolo