[OpenBIOS] OpenSolaris starts to live on SPARC64

[Blue Swirl]

On 4/3/10, Artyom Tarasenko <atar4qemu at googlemail.com> wrote:
> 2010/4/3 Mark Cave-Ayland <mark.cave-ayland at siriusit.co.uk>:
>
> > Mark Cave-Ayland wrote:
>  >  (I wonder if some MMU/CPU emulation is broken somewhere?)
>
>
> Actually a very good question. Does qemu emulate any sun4u
>  machine good enough to have a chance running with OBP?
>  It may be a good strategy for fixing the  "hardware".  At least
>  it was fruitful on sun4m.
>  Blue?

One problem with that strategy is that QEMU does not implement any
real machines now. Typical Ultra machines had HME NICs, 53C875 SCSI
controller but we have random PCI NICs and IDE (CMD646 exists but
usually it's only used for CDROM). OSes probably don't care whether
the machine matches any real one or not.

One solution would be to implement the first Ultra machines, which
were partially SBUS based and had many common devices with Sun4m.

We could also implement some mid-class machine with HME and 53C875 (it
may even be similar to lsi53c895a, which we have). PCI bridging does
not work well in QEMU. The docs aren't very good I think. This is
closest to what we have now. It could be interesting to see what OBP
from a real machine would think of the QEMU machine.

Third option would be to aim for T1/T2 class machines. The docs are
good and there is even Verilog implementation to compare with because
most of the devices are inside the CPU. The devices aren't very simple
and there is very little commonality with old HW. There are also CPU
features to be implemented (CMT). The boot ROM architecture is
interesting, there is a hypervisor which OBP uses. Everything is open
source, including the CPU. QEMU's Niagara machine can boot the
hypervisor, which will output a few lines before crashing.

The options aren't mutually exclusive, so if we had an infinite number
of monkeys we could advance in all three areas simultaneously. There's
a lot of playground. :-)