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?
