On 02/10/2011 04:29 AM, Avi Kivity wrote:
On 02/10/2011 09:47 AM, Anthony Liguori wrote:
So very concretely, I'm suggesting we do the following to target-i386:
1) make the i440fx device have an embedded ide controller, piix3, and
usb controller that get initialized automatically. The piix3 embeds
the PCI-to-ISA bridge along with all of the default ISA devices (rtc,
serial, etc.).
This I like.
2) get rid of the entire concept of machines. Creating a i440fx is
essentially equivalent to creating a bare machine.
No, it's not. The 440fx does not include an IOAPIC, for example.
There may be other optional components, or differences in wiring, that
make two machines with i440fx not identical.
The IOAPIC is basically the only other component and I view it as part
of the CPU interface to the chipset.
But still, if we're creating a machine from scratch:
qemu -device i440fx,id=nb -device piix3,id=sb,chipset=nb -device
ioapic,id=ioapic,chipset=sb -device cpu,ioapic=ioapic,northbridge=nb
Is not all that unreasonable and presents a fully functioning PC.
4) model the CPUs as devices that take a pointer to a host
controller, for x86, the normal case would be giving it a pointer to
i440fx.
Surely the connection is via a bus? An x86 cpu talks to the bus, and
there happens to be an 440fx north bridge at the end of it. It could
also be a Q35 or something else.
I see being on a bus as really just taking a pointer to an interface.
So yes, the i440fx would implement a PentiumCpuInterface or something
like that and the CPU would take a pointer to a PentiumCpuInterface[1].
This is part of why having proper polymorphism is important. We need it
in order to be able to express concepts like interfaces.
[1] This is just a Random Bad Name. Don't read anything into it.
Regards,
Anthony Liguori
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