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.
