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Date: Fri, 21 Nov 2014 00:08:15 -0800
Message-ID: <CAFgRE9F6MgjdMqz-kT3hvgB6YDwrxijoEVnGBFJfahK5mNpRrA@mail.gmail.com>
Subject: Re: 'repz' instruction not supported.
From: Neel Natu <neelnatu@gmail.com>
To: Ashutosh Kumar <mrashutosh@hotmail.com>
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Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org>
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Hi Ashutosh,

On Wed, Nov 19, 2014 at 10:30 PM, Ashutosh Kumar <mrashutosh@hotmail.com> wrote:
> Hi
> We have found that emulation of 'repz' instruction is not supported in bhyve. This is causing VM_EXIT for Guest OS. Do we have plans to add support for instructions like 'repz'.
>

'repz' is actually an instruction prefix. The two instructions with
which 'repz' is allowed are 'cmps' and 'scas'. Both these instructions
typically don't need to be emulated since they operate on strings in
"regular" guest memory.

Is your guest emitting these instructions to access MMIO? Can you
share an objdump with the offending instructions?

best
Neel

> RegardsAshutosh
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