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Date: Wed, 20 Aug 2014 18:32:58 +0200
From: =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>
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To: John Baldwin <jhb@freebsd.org>, <freebsd-drivers@freebsd.org>
Subject: Re: Directly reserve an interrupt IDT entry for Hyper-V
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On 20/08/14 17:31, John Baldwin wrote:
> On Wednesday, August 20, 2014 9:31:54 am Roger Pau Monné wrote:
>> Hello,
>>
>> I don't think using the same IDT vector is the right approach, I would
>> just pick a different IDT vector and use that for Hyper-V. Using the
>> same IDT vector (like your suggestion above) would prevent shipping a
>> kernel with with both Hyper-V and Xen support (like it's done now in
>> GENERIC).
>>
>> Roger.
> 
> Hmm, can't you make this a runtime check to only call setidt() if you detect 
> you are under the appropriate hypervisor?
> 
> Also, bhyve currently has a hackish way of requesting a free IDT slot.  
> Perhaps it would be best if I added little API to reserve an IDT slot assuming 
> that callers could accept a dynamic IDT vector rather than a static one.

That would work for Xen. The IDT vector doesn't need to be fixed since
it's registered with Xen when the system boots.

Roger.