On 06/28/2018 01:40 PM, Andrea Bolognani wrote: > On Thu, 2018-06-28 at 12:04 +0200, Cédric Le Goater wrote: >> On 06/28/2018 10:00 AM, Andrea Bolognani wrote: >>> On Thu, 2018-06-28 at 13:59 +1000, David Gibson wrote: >>>> Well.. sure.. but it doesn't. pSeries is a virtual platform, so we >>>> have a reasonable amount of flexibility to define it as we want. >>>> PowerNV is an emulation of existing hardware which has a specific >>>> behaviour which we need to match. >>> >>> Sure, that's something to keep in mind. >>> >>> But the thing is, you still need to have *some* flexibility in >>> the number of PHBs, since there is variation among real Power8 >>> and Power9 chips; in the current incarnation, that flexibility >>> is provided by the num_phbs parameter, which is an entirely new >>> interface that's exclusive to PowerNV. >>> >>> What I'm suggesting is that the same amount of flexibility is >>> offered through a standard interface, namely -device, instead. >> >> Yes. I don't know to be honest. Adding support for -device is not >> complex. >> >> v2 proposes to initialize a fixed set of PHBs 2, 3, 4 depending on >> the CPU. I think this is the best modeling option to fit the HW. > > That approach would require even more hacks in libvirt if we ever > wanted to support PowerNV - basing the PCI address allocation on > the CPU model is not something that's really ever happened before.
ah. hmm, so that's another +1 for the -device approach. > To make it somewhat reasonable, information about the number of > PHBs created for each CPU model would have to be exposed through > QMP. And I wonder what a multi-chip guest would look like... > > Plus, as soon as you try something like > > $ qemu-system-ppc64 \ > -nodefaults -display none \ > -machine powernv -cpu POWER8E \ > -device pci-bridge,id=pci.1,chassis_nr=1,bus=pci.0,addr=0x1 \ > -device megasas,id=scsi0,bus=pci.1,addr=0x1 > > very interesting things will start happening :) Well it boots :) / # lspci 0000:00:00.0 PCI bridge: IBM POWER8 Host Bridge (PHB3) 0000:01:00.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge 0000:02:01.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge 0000:02:02.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 03) 0000:02:07.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) 0001:00:00.0 PCI bridge: IBM POWER8 Host Bridge (PHB3) 0001:01:00.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge 0001:02:01.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 C.
