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From: Jamie Lokier <jamie@shareable.org>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: Michael Walle <michael@walle.cc>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 2/4] Add support for execution from ROMs in IO device mode
Date: Thu, 13 May 2010 20:23:24 +0100	[thread overview]
Message-ID: <20100513192324.GA9388@shareable.org> (raw)
In-Reply-To: <5b7efeb30fe6f93a369b6a9f964a2cb7c0519222.1273760202.git.jan.kiszka@web.de>

Jan Kiszka wrote:
> While IO_MEM_ROMD marks an I/O memory region as "read/execute from RAM,
> but write to I/O handler", there is no flag indicating that an I/O
> region which is fully managed by I/O handlers can still be hosting
> executable code. One use case for this are flash device models that
> switch to I/O mode during reprogramming. Not all reprogramming states
> modify to read data, thus practically allow to continue execution.
> Moreover, we need to avoid switching the modes too frequently for
> performance reasons which requires fetching opcodes while still in I/O
> device mode.

I like this change.

Does "fetching opcodes while still in I/O device mode" fetch opcodes
from the RAM backing, or via the I/O read handlers?

If the latter, I'm wondering how KVM would cope with that.

Thanks,
-- Jamie

  reply	other threads:[~2010-05-13 19:23 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-13 14:16 [Qemu-devel] [PATCH 0/4] Fix the lazy CFI mode switch Jan Kiszka
2010-05-13 14:16 ` [Qemu-devel] [PATCH 1/4] cfi02: Fix a debug print Jan Kiszka
2010-05-13 14:16 ` [Qemu-devel] [PATCH 2/4] Add support for execution from ROMs in IO device mode Jan Kiszka
2010-05-13 19:23   ` Jamie Lokier [this message]
2010-05-13 20:10     ` Jan Kiszka
2010-05-13 20:24       ` Jan Kiszka
2010-05-13 14:16 ` [Qemu-devel] [PATCH 3/4] cfi: Mark flash memory executable Jan Kiszka
2010-05-13 14:16 ` [Qemu-devel] [PATCH 4/4] cfi02: Use timer-based ROM mode switch Jan Kiszka

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