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From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 18 Aug 2017 09:59:41 +0100
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Subject: Re: [Qemu-devel] [Bug 1706296] Re: Booting NT 4 disk causes
 /home/rjones/d/qemu/cpus.c:1580:qemu_mutex_lock_iothread: assertion failed:
 (!qemu_mutex_iothread_locked())
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To: =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>
Cc: Bug 1706296 <1706296@bugs.launchpad.net>, QEMU Developers <qemu-devel@nongnu.org>

On 18 August 2017 at 09:40, Alex Benn=C3=A9e <alex.bennee@linaro.org> wrote=
:
>
> John Arbuckle <programmingkidx@gmail.com> writes:
>
>> Using '-cpu 486' gets past the assertion error. I guess Windows NT 4.0
>> is not compatible with newer Intel processors.
>
> It might be related. The assertion error is caused by the fact an
> exception has occurred and processor is trying to dump a stack frame that
> overlaps from RAM into device memory. As the IRQ/exception handling is
> already under the BQL (as it changes machine state) we get the assertion
> when it tries to take the BQL a second time when accessing device
> memory.

This sounds worrying -- lots and lots of target backend code
does writes to memory. Is it all going to cause assertions if
it happens to be pointing at a device?

thanks
-- PMM