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Re: [Qemu-devel] [PATCH 2/4] Add support for execution from ROMs in IO d
From: |
Jamie Lokier |
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 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
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