[OpenBIOS] fdthree

[Blue Swirl]

On Mon, May 14, 2012 at 4:26 PM, Artyom Tarasenko <atar4qemu at gmail.com> wrote:
> Since none of the current Linux/sparc64 distributions has virtio
> drivers out of the box, it were nice to give the user ability to load
> them from a removable media.
> Currently Linux doesn't recognize our fdthree drive. The reason is
> simple - in OpenBIOS
>
> 0 > cd /pci/ebus/fdthree  ok
> 0 > .properties
> name                      "fdthree"
> reg                       00000000 00000000 00000000
>
> in ultra5's prtconf this property looks like this:
>
> reg:  00000014.003023f0.00000008.00000014.00706000.00000010.00000014.00720000.00000004
>
> The meaning of the first triple is clear - these are the fdc control
> registers. But what are the two other register sets?
>
> It looks like qemu has a normal PC floppy, connected to EBus. Probably
> it's not what Sun used to call fdthree?
> If fdthree is really something else, were there any UltraSPARC
> machines with PC floppy drives?

I think the FDC was pretty standard 82077. The additional registers
could implement a DMA controller. At least OpenBSD only seems to use
the 82077 registers:
http://fxr.watson.org/fxr/source/arch/sparc64/dev/fd.c?v=OPENBSD

>
> --
> Regards,
> Artyom Tarasenko
>
> solaris/sparc under qemu blog: http://tyom.blogspot.com/search/label/qemu
>
> --
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