Re: [Qemu-devel] [PATCH v2 04/10] fdc: emulate stepping 0

[Kevin Wolf]

Am 15.01.2012 08:51, schrieb Hervé Poussineau:
> Stepping 1 (S82078B) is not fully i82078 compatible, so better stick to 
> initial revision
> 
> Signed-off-by: Hervé Poussineau <address@hidden>
> ---
>  hw/fdc.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/fdc.c b/hw/fdc.c
> index bedaeca..0e167f8 100644
> --- a/hw/fdc.c
> +++ b/hw/fdc.c
> @@ -1385,7 +1385,7 @@ static void fdctrl_handle_version(FDCtrl *fdctrl, int 
> direction)
>  
>  static void fdctrl_handle_partid(FDCtrl *fdctrl, int direction)
>  {
> -    fdctrl->fifo[0] = 0x41; /* Stepping 1 */
> +    fdctrl->fifo[0] = 0x01; /* Stepping 0 */
>      fdctrl_set_fifo(fdctrl, 1, 0);
>  }
>  

Hm, this is the kind of change that I'm hesitant to make because I don't
understand the implications. Can you give some more details what is
fixed by this and why you think it's harmless for currently working OSes?

My spec says this:

     6 3 14 PART ID COMMAND
    This command can be used to identify the floppy
    disk controller as an enhanced controller The first
    stepping of the 82078 (all 44 pin versions) will yield
    0x41 in the result phase of this command Any future
    enhancements on these parts will be denoted by the
    5 LSBs (0x01 to 0x1F)

It doesn't even define what 0x01 would mean.

Kevin