On 08/02/17 15:47, Michael S. Tsirkin wrote: > On Wed, Aug 02, 2017 at 12:23:46AM +0200, Laszlo Ersek wrote: >> On 08/01/17 23:39, Michael S. Tsirkin wrote: >>> On Wed, Aug 02, 2017 at 12:33:12AM +0300, Alexander Bezzubikov wrote: >>>> 2017-08-01 23:31 GMT+03:00 Laszlo Ersek <ler...@redhat.com>: >>>>> (Whenever my comments conflict with Michael's or Marcel's, I defer to >>>>> them.) >>>>> >>>>> On 07/29/17 01:37, Aleksandr Bezzubikov wrote: >>>>>> Signed-off-by: Aleksandr Bezzubikov <zuban...@gmail.com> >>>>>> --- >>>>>> docs/pcie.txt | 46 ++++++++++-------- >>>>>> docs/pcie_pci_bridge.txt | 121 >>>>>> +++++++++++++++++++++++++++++++++++++++++++++++ >>>>>> 2 files changed, 147 insertions(+), 20 deletions(-) >>>>>> create mode 100644 docs/pcie_pci_bridge.txt >>>>>> >>>>>> diff --git a/docs/pcie.txt b/docs/pcie.txt >>>>>> index 5bada24..338b50e 100644 >>>>>> --- a/docs/pcie.txt >>>>>> +++ b/docs/pcie.txt >>>>>> @@ -46,7 +46,7 @@ Place only the following kinds of devices directly on >>>>>> the Root Complex: >>>>>> (2) PCI Express Root Ports (ioh3420), for starting exclusively PCI >>>>>> Express >>>>>> hierarchies. >>>>>> >>>>>> - (3) DMI-PCI Bridges (i82801b11-bridge), for starting legacy PCI >>>>>> + (3) PCIE-PCI Bridge (pcie-pci-bridge), for starting legacy PCI >>>>>> hierarchies. >>>>>> >>>>>> (4) Extra Root Complexes (pxb-pcie), if multiple PCI Express Root >>>>>> Buses >>>>> >>>>> When reviewing previous patches modifying / adding this file, I >>>>> requested that we spell out "PCI Express" every single time. I'd like to >>>>> see the same in this patch, if possible. >>>> >>>> OK, I didn't know it. >>>> >>>>> >>>>>> @@ -55,18 +55,18 @@ Place only the following kinds of devices directly >>>>>> on the Root Complex: >>>>>> pcie.0 bus >>>>>> >>>>>> ---------------------------------------------------------------------------- >>>>>> | | | | >>>>>> - ----------- ------------------ ------------------ >>>>>> -------------- >>>>>> - | PCI Dev | | PCIe Root Port | | DMI-PCI Bridge | | pxb-pcie >>>>>> | >>>>>> - ----------- ------------------ ------------------ >>>>>> -------------- >>>>>> + ----------- ------------------ ------------------- >>>>>> -------------- >>>>>> + | PCI Dev | | PCIe Root Port | | PCIE-PCI Bridge | | pxb-pcie >>>>>> | >>>>>> + ----------- ------------------ ------------------- >>>>>> -------------- >>>>>> >>>>>> 2.1.1 To plug a device into pcie.0 as a Root Complex Integrated >>>>>> Endpoint use: >>>>>> -device <dev>[,bus=pcie.0] >>>>>> 2.1.2 To expose a new PCI Express Root Bus use: >>>>>> -device pxb-pcie,id=pcie.1,bus_nr=x[,numa_node=y][,addr=z] >>>>>> - Only PCI Express Root Ports and DMI-PCI bridges can be connected >>>>>> + Only PCI Express Root Ports, PCIE-PCI bridges and DMI-PCI bridges >>>>>> can be connected >>>>> >>>>> It would be nice if we could keep the flowing text wrapped to 80 chars. >>>>> >>>>> Also, here you add the "PCI Express-PCI" bridge to the list of allowed >>>>> controllers (and you keep DMI-PCI as permitted), but above DMI was >>>>> replaced. I think these should be made consistent -- we should make up >>>>> our minds if we continue to recommend the DMI-PCI bridge or not. If not, >>>>> then we should eradicate all traces of it. If we want to keep it at >>>>> least for compatibility, then it should remain as fully documented as it >>>>> is now. >>>> >>>> Now I'm beginning to think that we shouldn't keep the DMI-PCI bridge >>>> even for compatibility and may want to use a new PCIE-PCI bridge >>>> everywhere (of course, except some cases when users are >>>> sure they need exactly DMI-PCI bridge for some reason) >>> >>> Can dmi-pci support shpc? why doesn't it? For compatibility? >> >> I don't know why, but the fact that it doesn't is the reason libvirt >> settled on auto-creating a dmi-pci bridge and a pci-pci bridge under >> that for Q35. The reasoning was (IIRC Laine's words correctly) that the >> dmi-pci bridge cannot receive hotplugged devices, while the pci-pci >> bridge cannot be connected to the root complex. So both were needed. >> >> Thanks >> Laszlo > > OK. Is it true that dmi-pci + pci-pci under it will allow hotplug > on Q35 if we just flip the bit in _OSC?
Marcel, what say you?... :)
