Re: [Qemu-devel] [PATCH v2 1/2] ppc/pnv: Add model for Power8 PHB3 PCIe Host bridge

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2018-07-27 at 10:25 +0200, Cédric Le Goater wrote:
> Each PHB creates a pci-bridge device and the PCI bus that comes with it. 
> It makes things easier to define PCI devices. 
> 
> It is still quite complex ... Here is a sample :
> 
> qemu-system-ppc64 -m 2G -machine powernv \
>   -cpu POWER8 -smp 2,cores=2,threads=1 -accel tcg,thread=multi \
>   -kernel ./zImage.epapr -initrd ./rootfs.cpio.xz -bios ./skiboot.lid \
>   \
>   -device megasas,id=scsi0,bus=pci.0,addr=0x1 \
>   -drive file=./rhel7-ppc64le.qcow2,if=none,id=drive-scsi0-0-0-0,format=qcow2,cache=none \
>   -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=2 \
>   \
>   -device ich9-ahci,id=sata0,bus=pci.1,addr=0x1 \
>   -drive file=./ubuntu-ppc64le.qcow2,if=none,id=drive0,format=qcow2,cache=none \
>   -device ide-hd,bus=sata0.0,unit=0,drive=drive0,id=ide,bootindex=1 \
>   -device e1000,netdev=net0,mac=C0:FF:EE:00:00:02,bus=pci.1,addr=0x2 \
>   -netdev bridge,helper=/usr/libexec/qemu-bridge-helper,br=virbr0,id=net0 \
>   -device nec-usb-xhci,bus=pci.1,addr=0x7 \

I don't understand why. That means you can't put emulated (or real)
PCIe device below it ? Why force them down the path of having a bridge
to legacy PCI always ?

My original intent was to have one such bridge in a machine for the
various default PCI devices qemu has that aren't (yet) PCIe (and also
for testing :-) but I never thought we'd throw one onto every PCIe bus.

Ben.