Re: [Qemu-devel] i386: EFER vs 32-bit CPU

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Pavel Dovgalyuk (dovgaluk@ispras.ru) wrote:
> Hello!
> 
>  
> 
> I found this while debugging the inconsistent saved/restored state of the virtual machine.
> 
>  
> 
> i386 (32 bit) emulation uses this register (in wrmsr and in MMU fault processing).
> 
> But it does not included in VMState, because "efer" field is disabled with #ifdef TARGET_X86_64
> 
>  
> 
> I think that efer should be saved for i386 too, but how it should be made to preserve the backward
> compatibility?
> 
> Should we add a section for i386, which duplicates efer, or just version_id of the main VMSD should
> be updated?

You could do:

#ifdef TARGET_X86_64
        VMSTATE_UINT64(env.efer, X86CPU),
        VMSTATE_UINT64(env.star, X86CPU),
...

to become:

        VMSTATE_UINT64_TEST(env.efer, X86CPU, efer_needed)
#ifdef TARGET_X86_64
        VMSTATE_UINT64(env.star, X86CPU),


and then make efer_needed a function that returns true if
TARGET_X86_64 or it's a new machine type that knows about whatever
you're going to do with it.

Dave

>  
> 
> Pavel Dovgalyuk
> 
>  
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK