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

[Jordan Justen]

On Thu, Mar 10, 2011 at 14:31, Carl-Daniel Hailfinger
<address@hidden> wrote:
> Right, the constant size argument is definitely a point we need to talk
> about.
>
> We could sidestep the issue by always using a 16 MByte flash device
> which gets filled from the top with the firmware image, but I'm not sure
> if that has other side effects.
> Another way to solve this would be to emulate multiple flash chips, one
> per power-of-two size between 128 kB and 16 MB. Some SPI flash chip
> families encode the size into their ID, so determining the size
> algorithmically is as simple as calculating
> 1 << idbyte3
> and emulating this is equally simple.

Power of 2 from 128kb to 16MB sounds reasonable to me.

How would the SPI host controller be discovered?  Would the firmware
be able to depend on having control of the device at OS runtime?  This
would be needed for UEFI non-volatile variables to make sure they can
always be written.

Thanks,

-Jordan