On Fri, Sep 08, 2023 at 01:50:36AM -0700, Christoph Hellwig wrote: > On Thu, Sep 07, 2023 at 10:04:10PM -0600, Alex Williamson wrote: > > > I think it really depends on what the qemu side wants to do.. > > > > Ok, I thought you had been one of the proponents of the fake BAR > > approach as more resembling CXL. Yes, I do prefer this because it is ultimately simpler on the qemu and VM side. This ACPI tinkering is not nice. > > Do we need to reevaluate that the tinkering with the VM machine > > topology and firmware tables would better align to a device > > specific region that QEMU inserts into the VM address space so > > that bare metal and virtual machine versions of this device look > > more similar? Thanks, > Yes, providing something to a VM that doesn't look anything like the > underlying hardware feels pretty strange. I don't see the goal as perfect emulation of the real HW. Aiming for minimally disruptive to the ecosystem to support this quirky pre-CXL HW. Perfect emulation would need a unique VFIO uAPI and more complex qemu changes, and it really brings nothing of value. Jason
