On Mon, May 14, 2012 at 10:22 PM, Blue Swirl blauwirbel@gmail.com wrote:
On Mon, May 14, 2012 at 4:26 PM, Artyom Tarasenko atar4qemu@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.
It seems that in qemu the DMA controller sits on ISA, not on fdc? And that we don't have it in EBus? But I guess dma.c could be used directly as-is?
At least OpenBSD only seems to use the 82077 registers: http://fxr.watson.org/fxr/source/arch/sparc64/dev/fd.c?v=OPENBSD