On Thu, 2015-11-19 at 15:22 +0000, Eric Auger wrote: > I am resending this RFC from Oct 12, after kernel 4.4-rc1 and > QEMU 2.5-rc1, hoping things have calmed down a little bit. > > This RFC allows to set up AMD XGBE passthrough. This was tested on AMD > Seattle. > > The first upstreamed device supporting KVM platform passthrough was the > Calxeda Midway XGMAC. Compared to this latter, the XGBE XGMAC exposes a > much more complex device tree node. Generating the device tree node for > the guest is the challenging and controversary part of this series. > > - First There are 2 device tree node formats: > one where XGBE and PHY are described in separate nodes and another one > that combines both description in a single node (only supported by 4.2 > onwards kernels). Only the combined description is supported for passthrough, > meaning the host must be >= 4.2 and must feature a device tree with a combined > description. The guest will also be exposed with a combined description, > meaning only >= 4.2 guest are supported. It is not planned to support > separate node representation since assignment of the PHY is less > straigtforward. > > - the XGMAC/PHY node depends on 2 clock nodes (DMA and PTP). > The code checks those clocks are fixed to make sure they cannot be > switched off at some point after the native driver gets unbound. > > - there are many property values to populate on guest side. Most of them > cannot be hardcoded. That series proposes a way to parse the host device > tree blob and retrieve host values to feed guest representation. Current > approach relies on dtc binary availability plus libfdt usage. > Other alternatives were discussed in: > http://www.spinics.net/lists/kvm-arm/msg16648.html. > > - Currently host booted with ACPI is not supported.
I won't pretend to know all the politics in the ARM space, but doesn't this last bullet sort of imply that this is dead-on-arrival code? Maybe not in the embedded space, but certainly in the server space, I thought ACPI was declared the winner. Thanks, Alex
