Re: [Qemu-devel] Re: RFC: emulation of system flash

[Jan Kiszka <jan.kiszka@web.de>]

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On 2011-03-11 20:09, Jordan Justen wrote:
> On Thu, Mar 10, 2011 at 16:27, Carl-Daniel Hailfinger
> <c-d.hailfinger.devel.2006@gmx.net> wrote:
>> Auf 11.03.2011 01:19, Jan Kiszka schrieb:
>>> At least it's an in-band interface, which is the better choice as we
>>> currently only have a PIIX3 southbridge for x86, predating even FWHs.
>>>
>>
>> Right, that pretty much kills the option of using SPI unless someone
>> wants to emulate a flash translation controller (e.g. the ITE IT8716F
>> Super I/O). Can be done, would work, but the IT8716F has some quirks
>> (max 1 MB SPI flash chips) which make it a less desirable option for
>> emulation.
> 
> I don't much like this, but we might consider adding the SPI host
> controller MMIO just below the flash data.  For the firmware, we
> usually will know the size of firmware device that we've built for.
> It seems SPI flash is pretty common today, and it sounds like
> Carl-Daniel may have some SPI emulation code.

We don't emulate a chipset yet that includes SPI. Adding an artificial
SPI master is like PV - the guests will require special drivers.

> 
> Am I understanding correctly that CFI is programmed via MMIO in the
> flash memory space?  How difficult would it be to emulate CFI?  Does

Check qemu/hw/pflash_cfi02.c.

> CFI have the same power-of-2 size flexibility as SPI?

Yes.

Jan


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