[Qemu-devel] Re: POLL: Why do you use kqemu?

[Avi Kivity <avi@redhat.com>]

Jan Kiszka wrote:
>>>
>>> Check e.g the diff of hw/vga.c against upstream: All the magic dances
>>>  there are required as qemu-kvm tracking cpu_register_physical_memory and
>>>  kvm_log_start cannot cope with all the patterns normal qemu code comes
>>>  up with. Upstream slot management now provides the same features
>>>  (including migration) like qemu-kvm, it just does not deal with legacy,
>>>  thus it does not have to patch qemu code (rather, we were able to remove
>>>  some already merged hooks - vga_dirty_log_stop).
>>>       
>> Still not very restrictive, all this could be encapsulated with for
>> example macro COMPAT_NO_DMRW which could be removed when we don't care
>> anymore. Next?
>>     
>
> Really, it's not worth the maintenance pain: Every new device emulation
> code that wants to be KVM-legacy-compatible would need to be written
> like that. And unless you are familiar with the slot management
> internals, the "correct" pattern will not be obvious.
>   

Only devices which direct map memory.  Currently VGA and cirrus.



-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.