On Tue, Dec 23, 2014 at 06:30:15AM -0600, Michael Roth wrote: > This adds a general overview of hotplug/dynamic-reconfiguration > for sPAPR/pSeries guest. > > As specified in PAPR+ v2.7. > > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> > --- > docs/specs/ppc-spapr-hotplug.txt | 287 > +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 287 insertions(+) > create mode 100644 docs/specs/ppc-spapr-hotplug.txt > > diff --git a/docs/specs/ppc-spapr-hotplug.txt > b/docs/specs/ppc-spapr-hotplug.txt > new file mode 100644 > index 0000000..6f2863f > --- /dev/null > +++ b/docs/specs/ppc-spapr-hotplug.txt > @@ -0,0 +1,287 @@ > += sPAPR Dynamic Reconfiguration = > + > +sPAPR/"pseries" guests make use a facility called dynamic-reconfiguration to > +handle hotplugging of dynamic "physical" resources like PCI cards, or > +"logical"/paravirtual resources like memory, CPUs, and "physical" > +host-bridges, which are generally managed by the host/hypervisor and provided > +to guests as virtualized resources. The specifics of dynamic-reconfiguration > +are documented extensively in PAPR+ v2.7, Section 13.1. This document > +provides a summary of that information as it applies to the implementation > +within QEMU. > + > +== Dynamic-reconfiguration Connectors == > + > +To manage hotplug/unplug of these resources, a firmware abstraction known as > +a Dynamic Resource Connector (DRC) is used to assign a particular dynamic > +resource to the guest, and provide an interface for the guest to manage > +configuration/removal of the resource associated with it. > + > +== Device-tree description of DRCs == > + > +A set of 4 array Open Firmware device tree properties are used to describe > +the name/index/power-domain/type of each DRC allocated to a guest at > +boot-time. There may be multiple sets of these arrays, rooted at different > +paths in the device tree depending on the type of resource the DRCs manage. > + > +In some cases, the DRCs themselves may be provided by a dynamic resource, > +such as the DRCs managed PCI slots on a hotplugged PHB. In this case the > +arrays would be fetched as part of the device tree retrieval interfaces > +for hotplugged resources described under "Guest->Host interface". > + > +The array properties are described below. Each entry/element in an array > +describes the DRC identified by the element in the corresponding position > +of ibm,drc-indexes: > + > +ibm,drc-names: > + first 4-bytes: BE-encoded integer denoting the number of entries > + each entry: a NULL-terminated <name> string encoded as a byte array > + > + <name> values for logical/virtual resources are defined in PAPR+ v2.7, > + Section 13.5.2.4, and basically consist of the type of the resource > + followed by a space and a numerical value that's unique across resources > + of that type. > + > + <name> values for "physical" resources such as PCI or VIO devices are > + defined as being "location codes", which are the "location labels" of > + each encapsulating device, starting from the chassis down to the > + individual slot for the device, concatenated by a hyphen. This provides > + a mapping of resources to a physical location in a chassis for debugging > + purposes. For QEMU, this mapping is less important, so we assign a > + location code that confirms to naming specifications, but is simply a
s/confirms/conforms/
Otherwise, nice write up.
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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