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From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 25 Jan 2019 10:36:17 +0000
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Subject: Re: [Qemu-devel] [PATCH v2 2/5] pflash: flush rom device memory
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= <philmd@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, Laurent Vivier <lvivier@redhat.com>, Thomas Huth <thuth@redhat.com>, Qemu-block <qemu-block@nongnu.org>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, =?UTF-8?Q?Steffen_G=C3=B6rtz?= <contrib@steffen-goertz.de>, Jim Mussared <jim@groklearning.com>, Max Reitz <mreitz@redhat.com>, qemu-arm <qemu-arm@nongnu.org>, Joel Stanley <joel@jms.id.au>, Paolo Bonzini <pbonzini@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Julia Suvorova <jusual@mail.ru>, Richard Henderson <rth@twiddle.net>

On Fri, 25 Jan 2019 at 10:28, Stefan Hajnoczi <stefanha@gmail.com> wrote:
>
> On Thu, Jan 24, 2019 at 12:11:55PM +0100, Philippe Mathieu-Daud=C3=A9 wro=
te:
> > The device realize() is also executed before the guest is started, is
> > this call really necessary?
>
> My rationale was that machine init only happens before the guest is
> started while ->realize() is called by hotplug too.

Yes, but before realize the flash memory can't actually be
visible to the guest, so there's no need to invalidate anything.

> That said, can pflash devices be hotplugged?

I guess you could have one inside a hotplugged device in theory;
they can't be directly hotpluggged. (I bet that in practice
there are leaks though if you did do that, and we don't have
any devices that do so today.)

> If you guys prefer not flushing from pflash ->realize() then I'll drop
> it.

I think it makes more sense not to do a flush in the realize method.

thanks
-- PMM