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Date: Thu, 13 Nov 2008 13:56:41 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [5627] Add KVM support to QEMU
References: <E1Kxkrx-0006Lk-OG@cvs.savannah.gnu.org>
	<20081112104215.GA11733@lst.de>
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To: qemu-devel@nongnu.org, Christoph Hellwig <hch@infradead.org>

Christoph Hellwig wrote:
> On Wed, Nov 05, 2008 at 04:04:33PM +0000, Anthony Liguori wrote:
>   
>> +# kvm probe
>> +if test "$kvm" = "yes" ; then
>> +    cat > $TMPC <<EOF
>> +#include <linux/kvm.h>
>> +#if !defined(KVM_API_VERSION) || \
>> +    KVM_API_VERSION < 12 || \
>> +    KVM_API_VERSION > 12 || \
>> +    !defined(KVM_CAP_USER_MEMORY) || \
>> +    !defined(KVM_CAP_SET_TSS_ADDR)
>> +#error Invalid KVM version
>> +#endif
>>     
>
> The installed linux/kvm.h has no relatation at all to the currently
> running kernel.   Please ship a current max API version kvm.h with qemu
> and always build against that one, and handle lower API versions at
> runtime.  Please don't turn mainline qemu kvm support into the same
> bloody mess as the kvm userspace repository.
>   

There are multiple places in QEMU that depend on kernel headers.  I 
don't want to stick kvm headers in QEMU while depending on external 
headers for USB pass through.  If someone wants to put together a patch 
to make QEMU no longer depend on external headers, I'd happily 
review/apply it.  I expect it to be tested on various kernel versions 
though.  Some less than wonderful kernel subsystems have not always been 
good about making interface changes backwards compatible.  linux-aio is 
a good example of an interface that makes it exceedingly difficult to 
detect whether a new feature is supported on any given kernel version 
without doing a compile test.

Regards,

Anthony Liguori

>
>