Re: Make hvm_fep available to non-debug build as well?

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 14/06/16 11:54, Jan Beulich wrote:
>>>> On 14.06.16 at 12:47, <wei.liu2@citrix.com> wrote:
>> Andrew and I had a short conversation on IRC about why hvm_fep is only
>> available to debug build. Here is what he said:
>>
>> <andyhhp> liuw: because hvm_fep puts a very large attack surface back
>>           into the hypervisor
>> <andyhhp> I intoduced it originally to make it easy to test the
>>           instruction emulator without requiring a race condition between 
>> two
>>           vcpus
>> <andyhhp> so I guess paranoia is the underlying answer to your question
>> <andyhhp> there is nothing wrong in principle with making available in
>>           non-debug builds
>>
>> I think I agree with him that in principle it should be possible to
>> make hvm_fep available to non-debug build. Andrew also suggested a
>> sync_console style warning, which I think makes sense.
> Properly documented I'm not heavily opposed (but also not fully
> convinced of this being a good idea).

I have had one case where I needed to make FEP available in non-debug
build, as a bug I was chasing had its repro symptoms disappeared in a
debug build. 
(https://github.com/xenserver/xen-4.6.pg/commit/5826deab561dd92efaaeeb222c27184be257fad5
for those who are interested)

So long as it is obvious when it is enabled, I am a hesitant +1.

~Andrew

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