QEMU provides the following watchdog options for the x86_64 system emulator target

• ib700 - ISA only device, enabled X86_64
• ib6300esb - PCI device, enabled PPC64 & X86_64
• iTCO - PCI-E integrated device in Q35 chipset, enabled X86_64

The Q35 machine type has always had an integrated iTCO watchdog, but until fairly recently (QEMU 8.0.0 / libvirt 9.1.0) it was not really usable as it was not configurable in libvirt and the QEMU defaults won't trigger any action. There was also a window for Linux 5.15 -> 6.1 inclusive, where it was broken.

None the less the iTCO watchdog should be considered the default watchdog for QEMU going forward, since Q35 is the preferred machine type used by mgmt apps, and thus iTCO will be included everywhere out of the box.

While i440fx is deprecated, it is likely to exist indefinitely, and thus a standalone watchdog is useful to provide.

Since it is an ISA device, ib700 is x86 only, whereas the ib6300esb should be portable to any architecture target. Thus it is useful for other aches which lack a built-in watchdog in their machine types.

IOW,

• On non-x86 ib6300esb is useful as it is potentially the only watchdog available.
• On x86, ib6300esb is useful for i440fx and as a fallback for iTCO

It does not look like we especially need a 2nd fallback on x86 for the Q35 machine type, and i440fx is deprecated. Thus I'd suggest we can deprecate ib700 in RHEL-10, with a view to removing it in RHEL-11.

ib700 doesn't have any real engineering cost to retain, but eventual removal should reduce the QE test plan matrix costs.