[Qemu-devel] Re: [PATCHv4 15/15] Pass boot device list to firmware.

[Blue Swirl <blauwirbel@gmail.com>]

2010/11/16 Gleb Natapov <gleb@redhat.com>:
> On Tue, Nov 16, 2010 at 06:30:19PM +0000, Blue Swirl wrote:
>> >> Perhaps the FW path should use device class names if no name is specified.
>> > What do you mean by "device class name". We can do something like this:
>> > if (dev->child_bus.lh_first)
>> >        return dev->child_bus.lh_first->info->name;
>> >
>> > i.e if there is child bus use its bus name as fw name. This will make
>> > all pci devices to have "pci" as fw name automatically. The problem is
>> > that theoretically same device can provide different buses.
>>
>> I meant PCI class name, like "display" for display controllers,
>> "network" for NICs etc.
>>
> That is what my pci bus related patch is doing already.
>
>> >> I'll try Sparc32 to see how this fits there.
>>
>> Except bootindex is not implemented for SCSI.
> Will look into adding it.

Thanks. The bootindex on Sparc32 looks like this:
bootindex /esp@0000000078800000/disk@1,0
/ethernet@ffffffffffffffff/ethernet-phy@0

I don't think I got Lance setup right.

OF paths for the devices would be:
/iommu@0,10000000/sbus@0,10001000/espdma@5,8400000/esp@5,8800000/sd@1,0
/iommu@0,10000000/sbus@0,10001000/ledma@5,8400010/le@5,8c00000

The logic for ESP is that ESP (registers at 0x78800000, slot offset
0x880000) is handled by the DMA controller (registers at 0x78400000,
slot offset 0x840000), they are in a SBus slot #5, and SBus (registers
at 0x10001000) is in turn handled by IOMMU (registers at 0x10000000).
Lance should be handled the same way.

This hierarchy is partly known by QEMU because DMA accesses use this
flow, but not otherwise. There is no concept of SBus slots, DMA talks
to IOMMU directly. Though in this case both ESP, Lance and their DMA
controllers are on board devices in a MACIO chip. It may be possible
to add the hierarchy information at each stage.

It should also be possible for BIOS to determine the device just from
the physical address if we ignored OF compatibility.