On 16/12/2014 20:00, Laszlo Ersek wrote:
> Yes.
>
> The root of this question is what each of
>
> enum device_endian {
> DEVICE_NATIVE_ENDIAN,
> DEVICE_BIG_ENDIAN,
> DEVICE_LITTLE_ENDIAN,
> };
Actually, I think the root of the answer :) is that fw_cfg_read (and
thus fw_cfg_data_mem_read) is not idempotent. The split/compose stuff
accesses the bytes at offsets 8,9,10,11,12,13,14,15 and composes them
according to the endianness.
In the case of fw_cfg it just retrieves 8 bytes, but in the case of host
big endian it reads them in the "wrong" order for some reason (sorry, I
haven't looked at this thoroughly).
So the solution is:
1) make fw_cfg_data_mem_ops DEVICE_LITTLE_ENDIAN
2) make fw_cfg_data_mem_read and fw_cfg_data_mem_write call fw_cfg_read
and fw_cfg_write SIZE times and build up a value from the lowest byte up.
Paolo
