[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host b
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges |
Date: |
Wed, 23 May 2018 02:38:52 +0300 |
On Tue, May 22, 2018 at 03:47:41PM -0600, Alex Williamson wrote:
> On Wed, 23 May 2018 00:44:22 +0300
> "Michael S. Tsirkin" <address@hidden> wrote:
>
> > On Tue, May 22, 2018 at 03:36:59PM -0600, Alex Williamson wrote:
> > > On Tue, 22 May 2018 23:58:30 +0300
> > > "Michael S. Tsirkin" <address@hidden> wrote:
> > > >
> > > > It's not hard to think of a use-case where >256 devices
> > > > are helpful, for example a nested virt scenario where
> > > > each device is passed on to a different nested guest.
> > > >
> > > > But I think the main feature this is needed for is numa modeling.
> > > > Guests seem to assume a numa node per PCI root, ergo we need more PCI
> > > > roots.
> > >
> > > But even if we have NUMA affinity per PCI host bridge, a PCI host
> > > bridge does not necessarily imply a new PCIe domain.
> >
> > What are you calling a PCIe domain?
>
> Domain/segment
>
> 0000:00:00.0
> ^^^^ This
Right. So we can thinkably have PCIe root complexes share an ACPI segment.
I don't see what this buys us by itself.
> Isn't that the only reason we'd need a new MCFG section and the reason
> we're limited to 256 buses? Thanks,
>
> Alex
I don't know whether a single MCFG section can describe multiple roots.
I think it would be certainly unusual.
--
MST
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, (continued)
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Laszlo Ersek, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Marcel Apfelbaum, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Laszlo Ersek, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Michael S. Tsirkin, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Alex Williamson, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Michael S. Tsirkin, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Alex Williamson, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Laszlo Ersek, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Alex Williamson, 2018/05/23
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Michael S. Tsirkin, 2018/05/23
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Alex Williamson, 2018/05/23
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Michael S. Tsirkin, 2018/05/23
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Marcel Apfelbaum, 2018/05/23
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Alex Williamson, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Michael S. Tsirkin, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Laszlo Ersek, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Laszlo Ersek, 2018/05/22
- Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges, Marcel Apfelbaum, 2018/05/23