Re: [Qemu-devel] [RFC] Writeable files in fw_cfg

[David Woodhouse]

On Mon, 2013-01-28 at 08:36 -0800, Jordan Justen wrote:
> 
> What is need is for pflash_cfi01 to start in plain rom/executable mode
> while firmware executes from it during early boot.
> 
> Then later, after the rom has been shadowed, firmware will want to
> write to that memory space to program it. At that point it no longer
> needs to be executable.
> 
> So the question is, can it start out in rom/executable mode, but
> change into a non-executable mode if a write occurs? Will qemu get a
> chance to respond if something is written to a rom region, or is it
> silently ignored?
> 
> Also, once the 'read-array' command is written to it after programming
> is finished, can it revert to executable rom mode?

We often have separate gating in hardware to enable the write line (or
Vpp) to flash chips. Can we emulate that and use it to switch the flash
between executable and MMIO mode? Rather than being able to trap the
first write and see what it was...

-- 
dwmw2

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