[vbox-dev] host calling into vm for async I/O?

Sander van Leeuwen Sander.Vanleeuwen at Sun.COM
Tue Jul 15 01:15:28 PDT 2008


Let me clarify this a bit more on the blocking case. Inside the guest 
you need to create a (kernel) thread that calls the host HGCM service 
and waits for an answer, which it will get when the host service detects 
a directory change. As the host service is single threaded, you need to 
create a separate thread that monitors for directory changes. That 
additional host thread will asynchronously complete the HGCM service 
call the guest makes.
This means the HGCM service call made by the guest is not completed 
inside the svcCall handler (by calling g_pHelpers->pfnCallComplete).

Sander

Sander van Leeuwen wrote:
> There's is no such reversed callback mechanism for HGCM. You'd either 
> have to poll or make a guest thread block in a wait for directory 
> change HGCM call. The latter
> is not that easy as an HGCM client is single threaded.
>
> Sander
>
>
> Huihong Luo wrote:
>>
>> Are there any APIs that can invoke vm's functions from host (opposite 
>> to VbglHGCMCall which does vm to host calls)?
>>
>> I am trying to implement directory change notification features on 
>> windows shared folders. Basically, when files change in a host 
>> folder, I want the host to invoke a callback function inside vm.
>>
>>  
>>
>> Thanks,
>>
>>  
>>
>> Huihong
>>
>> ------------------------------------------------------------------------
>>
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>>   
>
>
> -- 
> Kind regards / Mit freundlichen Gruessen / Met vriendelijke groet
>
> --
>
> Sun Microsystems GmbH        Sander van Leeuwen
> Werkstrasse 24               Senior Staff Engineer, VirtualBox
> 71384 Weinstadt, Germany     mailto:Sander.Vanleeuwen at sun.com
>
>
> ================================================
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-- 
Kind regards / Mit freundlichen Gruessen / Met vriendelijke groet

--

Sun Microsystems GmbH        Sander van Leeuwen
Werkstrasse 24               Senior Staff Engineer, VirtualBox
71384 Weinstadt, Germany     mailto:Sander.Vanleeuwen at sun.com


================================================
Sitz der Gesellschaft: Sun Microsystems GmbH,
Sonnenallee 1, 85551 Kirchheim-Heimstetten
Amtsgericht Muenchen: HRB 161028
Geschaeftsfuehrer: Thomas Schroeder,
Wolfgang Engels, Dr. Roland Boehmer
Vorsitzender des Aufsichtsrates: Martin Haering
================================================

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