[Qemu-devel] How to generate custom fw paths for IDE devices?

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

Hi all,

Following on from a couple of patches I've previously posted to the 
mailing list at 
https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg08836.html I've 
made some good progress with trying to add bootindex support to OpenBIOS 
but I'm stuck with generating the IDE device paths from QEMU.

According to OpenBIOS the device path for a cdrom on a sun4u machine 
should be:

   /pci@1fe,0/pci@1,1/ide@3/ide1@8100/cdrom@0

whereas with my working patchset I'm currently generating:

   /pci@1fe,0/pci@1,1/ide@3/drive@1

The issue is that the drive@1 part is being generated by the IDE drive 
device attached to the IDE bus in hw/ide/qdev.c, and so I think I need 
to override idebus_get_fw_dev_path() to manually generate the remainder 
of the path including both the controller and the correctly named drive 
node.

One option may be to consider subclassing IDEBus and overriding 
idebus_get_fw_dev_path() there, but the cmd646 device is a child of 
TYPE_PCI_IDE which has its own internal IDEBus and so it seems 
overriding it is impossible.

Can anyone point me in the right direction as to how to generate the 
correct fw path for IDE devices in the above format for sun4u machines?


ATB,

Mark.