On 4/27/21 7:16 PM, John Snow wrote:
On 4/27/21 9:54 AM, Stefan Hajnoczi wrote:
I suggest fixing this at the qdev level. Make piix3-ide have a
sub-device that inherits from ISA_DEVICE so it can only be instantiated
when there's an ISA bus.
Stefan
My qdev knowledge is shaky. Does this imply that you agree with the
direction of Thomas's patch, or do you just mean to disagree with Phil
on his preferred course of action?
My understanding is a disagreement to both, with a 3rd direction :)
I agree with Stefan direction but I'm not sure (yet) that a sub-device
is the best (long-term) solution. I guess there is a design issue with
this device, and would like to understanding it first.
IIUC Stefan says the piix3-ide is both a PCI and IDE device, but QOM
only allow a single parent. Multiple QOM inheritance is resolved as
interfaces, but PCI/IDE qdev aren't interfaces, rather abstract objects.
So he suggests to embed an IDE device within the PCI piix3-ide device.
My view is the PIIX is a chipset that share stuffs between components,
and the IDE bus belongs to the chipset PCI root (or eventually the
PCI-ISA bridge, function #0). The IDE function would use the IDE bus
from its root parent as a linked property.
My problem is currently this device is user-creatable as a Frankenstein
single PCI function, out of its chipset. I'm not sure yet this is a
dead end or I could work something out.
Regards,
Phil.