Re: [Qemu-devel] Re: Host <-> guest interface port?

[Fabrice Bellard <fabrice@bellard.org>]

I would prefer a network based solution first. Changing the interface to 
use a CPU specific hack won't be difficult in the future.

Fabrice.

Matthew Mastracci wrote:
> Fabrice Bellard wrote:
> 
>> Matthew Mastracci wrote:
>>
>>> Would it be possible to add a host/guest interface port, akin to how 
>>> VMWare handles this?  It's a convenient way to get/set various 
>>> properties from the host while running the guest operating system.  
>>> This also allows a smoother mouse interface - ie: auto 
>>> capture/release of the mouse as it hits the screen boundaries, 
>>> clipboard synchronization as well as synchronization of the guest's 
>>> clock with the host's.
>>>
>>> Some more info on the VMWare port is here:
>>> http://chitchat.at.infoseek.co.jp/vmware/backdoor.html
>>
>>
>>
>> Of course it is possible to add that, but first we must define the 
>> features we want and implement the necessary support in the guest 
>> OSes, which seems to be the most difficult AFAIK. Clipboard support 
>> would be interesting. Does anyone know how to implement it for Linux 
>> and Windows guests ?
>>
> I can implement text-clipboard-passing for a windows guest without much 
> effort.  If the CPU protection for the IO port is disabled, even when 
> running at IOPL3, it could be implemented entirely in userspace.
> 
> It would be nice to define standard register values for the different 
> features, as well as add functionality to query the availability of the 
> feature.  For instance, the first two registers could define the 
> supported interface:
> 
> Register 0: Returns the maximum supported register index by the current 
> version of QEMU
> Register 1: Write to the register with a given register index - returns 
> 1 if supported or 0 if unsupported or disabled.
> 
> Possible register functionality (off the top of my head):
> - Get host clock: returns the host clock time in UTC (useful for clock 
> sync between guest/host)
> - Get host clock TZ: returns the host clock offset relative to UTC
> - Set host's clipboard
> - Get host's clipboard
> - Attach/detach virtual device (floppy/cd/etc)
> - Transfer file (?)
> - Read guest filesystem