[libvirt] [RFC v4 00/13] qmp: query-device-slots command
Changelog --------- Changes v3 -> v4: * New compact representation of slot sets. * New generic code to automatically merge similar slots into a single entry in the command output while keeping implementations of the method simpler. * Example implementation of IDE and USB bus enumeration Changes v2 -> v3: * Implemented a "slot set" structure, where multiple slots can be reported by using integer ranges or lists for possible values for each property. Added a ValueSet struct, that can represent a set of values using either a simple list of values, or integer ranges. (Its JSON representation is very verbose, though. See comments below). * Removed the *Properties structs, and replaced them with a simple list of SlotOption structs. * DeviceSlotInfo is not an union anymore, removed the 'type' field only because there are no slot-type-specific fields in the current implementation, but we may add it back if necessary * The implementation is very quick and dirty, the main purpose of this RFC is to evaluate the schema and returned data. Changes v1 -> v2: * Don't show sysbus unless has_dynamic_sysbus is set for the machine type * Removed max-devices and devices properties * Introduced "non-slot" slot type, to explicitly indicate we are returning info on a bus that doesn't implement slot enumeration yet. * Return bus name instead of full QOM path on "bus" field * PCI: Replaced "addr" property (string parsed by property setter) with "device-number" uint32 property * PCI: return only one slot for PCIe ports Summary ------- This adds a new command to QMP: query-device-slots. It will allow management software to query possible slots where devices can be plugged. This implementation of the command will return: * Multiple PCI slots per bus, in the case of PCI buses; * One slot for each entry from query-hotpluggable-cpus. * One slot per bus for the other buses (that don't implement slot enumeration yet), with opts-complete=false Representation of slot sets in JSON ----------------------------------- Slot sets are represented by a list of option names and sets of possible values for each of those options. The command uses a compact representation for the set of valid values for an option. For example, the following set of 5 PCI functions: bus: pcie.0 device-number: 31 functions: 1,4,5,6,7 would be represented in the JSON data as: {"available":false,"count":5, "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":[1,[4,7]]}, {"option":"device-number","values":31}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} I planned to use QAPI alternates to model/document that in the schema, but it would require implementing a few missing features in QAPI alternate support. TODO ---- * Differentiation between legacy-pci-device and pcie-device * Implement enumeration for other buses * Document the slotinfo.c functions * Optimize the slot/option merging algorithm Example output -------------- Using the following QEMU command-line: $ qemu-system-x86_64 -machine q35,accel=kvm \ -smp 16,maxcpus=32,threads=2,cores=2 query-device-slots will return the following entries: {"available":true,"count":224, "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":[[0,7]]}, {"option":"device-number","values":[[3,30]]}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":true,"count":1, "device-types":["ide-device"],"hotpluggable":false, "opts":[ {"option":"unit","values":0}, {"option":"bus","values":"ide.2"}], "opts-complete":true} {"available":true,"count":10, "device-types":["ide-device"],"hotpluggable":false, "opts":[ {"option":"unit","values":[[0,1]]}, {"option":"bus","values":["ide.4","ide.3","ide.5","ide.0","ide.1"]}], "opts-complete":true} {"available":true, "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":true,"count":16, "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":[[4,7]]}, {"option":"thread-id","values":[[0,1]]}, {"option":"core-id","values":[[0,1]]}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[16]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":3}, {"option":"thread-id","values":1}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[15]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":3}, {"option":"thread-id","values":0}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[14]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":3}, {"option":"thread-id","values":1}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[13]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":3}, {"option":"thread-id","values":0}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[12]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":2}, {"option":"thread-id","values":1}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[11]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":2}, {"option":"thread-id","values":0}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[10]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":2}, {"option":"thread-id","values":1}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[9]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":2}, {"option":"thread-id","values":0}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[8]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":1}, {"option":"thread-id","values":1}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[7]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":1}, {"option":"thread-id","values":0}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[6]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":1}, {"option":"thread-id","values":1}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[5]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":1}, {"option":"thread-id","values":0}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[4]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":0}, {"option":"thread-id","values":1}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[3]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":0}, {"option":"thread-id","values":0}, {"option":"core-id","values":1}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[2]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":0}, {"option":"thread-id","values":1}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[0]", "device-types":["qemu64-x86_64-cpu"],"hotpluggable":true, "opts":[ {"option":"socket-id","values":0}, {"option":"thread-id","values":0}, {"option":"core-id","values":0}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/q35/mch", "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":0}, {"option":"device-number","values":0}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":21, "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":[[1,7]]}, {"option":"device-number","values":[[0,2]]}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[44]", "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":0}, {"option":"device-number","values":1}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[45]", "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":0}, {"option":"device-number","values":2}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[18]", "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":0}, {"option":"device-number","values":31}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":5, "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":[1,[4,7]]}, {"option":"device-number","values":31}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[33]", "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":2}, {"option":"device-number","values":31}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[35]", "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":3}, {"option":"device-number","values":31}, {"option":"bus","values":"pcie.0"}], "opts-complete":true} {"available":false,"count":1,"device":"/machine/unattached/device[34]", "device-types":["ide-device"],"hotpluggable":false, "opts":[ {"option":"unit","values":1}, {"option":"bus","values":"ide.2"}], "opts-complete":true} {"available":false,"device":"/machine/unattached/device[32]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[31]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[30]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[29]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[28]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[27]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[26]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[25]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[24]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[23]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[22]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[20]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} {"available":false,"device":"/machine/unattached/device[19]", "device-types":["isa-device"],"hotpluggable":false, "opts":[ {"option":"bus","values":"isa.0"}], "opts-complete":false} Cc: Markus Armbruster <armbru@redhat.com> Cc: Marcel Apfelbaum <marcel@redhat.com> Cc: libvir-list@redhat.com Cc: Igor Mammedov <imammedo@redhat.com> Cc: Laine Stump <laine@redhat.com> Eduardo Habkost (13): qmp: Define query-device-slots command qapi: qobject_compare() helper qdev: Add BusClass::device_type field qdev: Slot info helpers query-device-slots: Collapse similar entries qdev core: generic enumerate_slots implementation qdev: Enumerate CPU slots on query-device-slots ide: enumerate_slots implementation pci: pci_bus_has_pcie_upstream_port() function pci: device-number & function properties pci: enumerate_slots implementation usb: enumerate_slots implementation tests: Experimental query-device-slots test code qapi-schema.json | 89 ++++++ include/hw/qdev-core.h | 5 + include/hw/qdev-slotinfo.h | 85 ++++++ include/hw/usb.h | 6 +- include/qapi/util.h | 39 +++ hw/audio/intel-hda.c | 7 + hw/block/fdc.c | 15 +- hw/char/virtio-serial-bus.c | 1 + hw/core/bus.c | 42 +++ hw/core/slotinfo.c | 610 ++++++++++++++++++++++++++++++++++++++++++ hw/core/sysbus.c | 8 + hw/i2c/core.c | 7 + hw/ide/qdev.c | 27 ++ hw/input/adb.c | 7 + hw/ipack/ipack.c | 7 + hw/isa/isa-bus.c | 1 + hw/misc/auxbus.c | 1 + hw/pci/pci.c | 120 ++++++++- hw/ppc/spapr_vio.c | 1 + hw/s390x/css-bridge.c | 2 + hw/s390x/event-facility.c | 1 + hw/s390x/s390-pci-bus.c | 7 + hw/scsi/scsi-bus.c | 1 + hw/sd/core.c | 7 + hw/ssi/ssi.c | 7 + hw/usb/bus.c | 37 +++ hw/usb/dev-smartcard-reader.c | 7 + hw/virtio/virtio-bus.c | 1 + qapi/qapi-util.c | 66 +++++ qdev-monitor.c | 109 ++++++++ tests/test-qapi-util.c | 53 ++++ tests/test-slotinfo.c | 398 +++++++++++++++++++++++++++ hw/core/Makefile.objs | 2 + tests/Makefile.include | 14 +- tests/qmp-machine-info.py | 300 +++++++++++++++++++++ 35 files changed, 2075 insertions(+), 15 deletions(-) create mode 100644 include/hw/qdev-slotinfo.h create mode 100644 hw/core/slotinfo.c create mode 100644 tests/test-slotinfo.c create mode 100755 tests/qmp-machine-info.py -- 2.9.4
This adds a new command to QMP: query-device-slots. It will allow management software to query possible slots where devices can be plugged. Slot sets are represented by a list of option names and sets of possible values for each of those options. We use a compact format for set of valid values, to keep JSON response size reasonable. The format is documented at the SlotOption struct. In the future, we may use QAPI alternates to define and document the exact data format more strictly. Actual implementations of BusClass::enumerate_slots will be added by other patches. Cc: Marcel Apfelbaum <marcel@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Cc: libvir-list@redhat.com, Cc: Igor Mammedov <imammedo@redhat.com> Cc: Laine Stump <laine@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- Changes v3 -> v4: * Use a more compact format for the "slot sets" * Renamed DeviceSlotInfo.props to DeviceSlotInfo.opts * Replaced DeviceSlotInfo.incomplete with DeviceSlotInfo.opts-complete * Now DeviceSlotInfo.available will be true even if hotplug is unavailable, to indicate the slot would be available using -device. Changes v2 -> v3: * Implemented a "slot set" structure, where multiple slots can be reported by using integer ranges or lists for possible values for each property. Added a ValueSet struct, that can represent a set of values using either a simple list of values, or integer ranges. (Its JSON representation is very verbose, though. See comments below). * Removed the *Properties structs, and replaced them with a simple list of SlotOption structs. * DeviceSlotInfo is not an union anymore, removed the 'type' field only because there are no slot-type-specific fields in the current implementation, but we may add it back if necessary * The implementation is very quick and dirty, the main purpose of this RFC is to evaluate the schema and returned data. Changes v1 -> v2: * Don't show sysbus unless has_dynamic_sysbus is set for the machine type * Removed max-devices and devices properties * Introduced "non-slot" slot type, to explicitly indicate we are returning info on a bus that doesn't implement slot enumeration yet. * Return bus name instead of full QOM path on "bus" field * PCI: Replaced "addr" property (string parsed by property setter) with "device-number" uint32 property * PCI: return only one slot for PCIe ports --- qapi-schema.json | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++ include/hw/qdev-core.h | 2 ++ qdev-monitor.c | 38 +++++++++++++++++++++ 3 files changed, 129 insertions(+) diff --git a/qapi-schema.json b/qapi-schema.json index 802ea53..6a9329e 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -4325,6 +4325,95 @@ ## { 'command': 'closefd', 'data': {'fdname': 'str'} } + +## +# @SlotOption: +# +# A option to be used when plugging a device to a slot. +# +# @option: Option name. +# +# @values: Set of valid option values. +# +# @values follow a compact format to represent a set of values: +# - If @values is a string, bool, or number, it representes a +# single-element set containing that value. In other words, +# @values is the only valid value for the option. +# - If @values is a list, each element E on the list represents +# one or more possible values for the option: +# - If E is a string, bool, or number, it indicates that E +# is a valid value for the option. +# - If E is a one-element list [V], it means V is a valid value +# for the option. +# - If E is a two-element list [A, B] where A and B are +# numbers, it means any number X, A <= X <= B is a valid +# value for the option. +# +# TODO: @values could be represented by nested 'alternate' types, +# for more consistent documentation and automatic +# validation/parsing, but the following limitations on +# alternates prevent that today: +# - alternate branches can't be lists +# - alternate string members conflict with scalar values +# - alternate types should have 2 or more branches +## +{ 'struct': 'SlotOption', + 'data': { 'option': 'str', 'values': 'any' } } + +## +# @DeviceSlotInfo: +# +# Information on a set of slots where devices can be plugged. +# +# @device-types: List of device types accepted by the slots. +# Any device plugged to the slot should implement +# one of the accepted device types. +# +# @device: QOM path of device plugged to the slot, if any. +# +# @available: If false, the slot is not available for plugging any device. +# This value can change at runtime if condition changes. +# +# @hotpluggable: If true, the slot accepts hotplugged devices. If false, +# device_add won't work on the slot even if @available=true. +# +# @count: Number of slots represented by this slot set. +# +# @opts-complete: If true, all options required to plug devices +# to slots in this set are present in @opts. If +# false, slot information is incomplete in this +# QEMU version and additional options may be +# required to plug devices on those slots. +# +# @opts: Information on the arguments that should be provided to +# @device_add if plugging a device to this slot. +# +# Incomplete Slot Sets +# -------------------- +# +# Slot sets with @opts-complete=false represent a bus that +# doesn't support slot enumeration yet. Slots of this type should +# be replaced by more detailed slot sets in future QEMU versions. +# +# If @count is omitted, the entry may or may not represent more +# than one slots. Future QEMU versions should include additional +# code to set @count on those entries. +## +{ 'struct': 'DeviceSlotInfo', + 'data': { 'device-types': [ 'str' ], '*device': 'str', + 'available': 'bool', 'hotpluggable': 'bool', + '*count': 'int', 'opts-complete': 'bool', + 'opts': [ 'SlotOption' ] } } + +## +# @query-device-slots: +# +# Return the list of possible slots for plugging devices using +# @device_add. +## +{ 'command': 'query-device-slots', + 'returns': [ 'DeviceSlotInfo' ] } + ## # @MachineInfo: # diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index ae31728..0111350 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -191,6 +191,8 @@ struct BusClass { void (*reset)(BusState *bus); BusRealize realize; BusUnrealize unrealize; + /*TODO: write doc */ + DeviceSlotInfoList *(*enumerate_slots)(BusState *bus); /* maximum devices allowed on the bus, 0: no limit. */ int max_dev; diff --git a/qdev-monitor.c b/qdev-monitor.c index 8fd6df9..785f4af 100644 --- a/qdev-monitor.c +++ b/qdev-monitor.c @@ -30,6 +30,8 @@ #include "qemu/help_option.h" #include "sysemu/block-backend.h" #include "migration/misc.h" +#include "qapi/qobject-output-visitor.h" +#include "hw/boards.h" /* * Aliases were a bad idea from the start. Let's keep them @@ -638,6 +640,42 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp) return dev; } +typedef struct SlotListState { + DeviceSlotInfoList *result; + DeviceSlotInfoList **next; +} SlotListState; + +static void append_slots(SlotListState *s, DeviceSlotInfoList *l) +{ + *s->next = l; + for (; l; l = l->next) { + s->next = &l->next; + } +} + +static int enumerate_bus(Object *obj, void *opaque) +{ + SlotListState *s = opaque; + + if (object_dynamic_cast(obj, TYPE_BUS)) { + BusState *bus = BUS(obj); + BusClass *bc = BUS_GET_CLASS(bus); + + if (bc->enumerate_slots) { + append_slots(s, bc->enumerate_slots(bus)); + } + } + return 0; +} + +DeviceSlotInfoList *qmp_query_device_slots(Error **errp) +{ + SlotListState s = { .next = &s.result }; + + object_child_foreach_recursive(qdev_get_machine(), enumerate_bus, &s); + return s.result; +} + #define qdev_printf(fmt, ...) monitor_printf(mon, "%*s" fmt, indent, "", ## __VA_ARGS__) static void qbus_print(Monitor *mon, BusState *bus, int indent); -- 2.9.4
On 08/14/2017 04:57 PM, Eduardo Habkost wrote:
Changelog ---------
Changes v3 -> v4: * New compact representation of slot sets. * New generic code to automatically merge similar slots into a single entry in the command output while keeping implementations of the method simpler. * Example implementation of IDE and USB bus enumeration
Slot sets are represented by a list of option names and sets of possible values for each of those options. The command uses a compact representation for the set of valid values for an option. For example, the following set of 5 PCI functions:
bus: pcie.0 device-number: 31 functions: 1,4,5,6,7
would be represented in the JSON data as:
{"available":false,"count":5, "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":[1,[4,7]]},
A list (and not just a single-type list, but a list that mixes scalar and sublist),
{"option":"device-number","values":31},
vs. a scalar. Why not a one-element array?
{"option":"bus","values":"pcie.0"}], "opts-complete":true}
I planned to use QAPI alternates to model/document that in the schema, but it would require implementing a few missing features in QAPI alternate support.
Yeah, I can see how existing QAPI alternates do not yet support arrays, which becomes important to your representation. Do you need help getting the QAPI generator improved to support a particular feature that you found to be lacking? -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
On Tue, Aug 15, 2017 at 01:57:50PM -0500, Eric Blake wrote:
On 08/14/2017 04:57 PM, Eduardo Habkost wrote:
Changelog ---------
Changes v3 -> v4: * New compact representation of slot sets. * New generic code to automatically merge similar slots into a single entry in the command output while keeping implementations of the method simpler. * Example implementation of IDE and USB bus enumeration
Slot sets are represented by a list of option names and sets of possible values for each of those options. The command uses a compact representation for the set of valid values for an option. For example, the following set of 5 PCI functions:
bus: pcie.0 device-number: 31 functions: 1,4,5,6,7
would be represented in the JSON data as:
{"available":false,"count":5, "device-types":["pci-device"],"hotpluggable":false, "opts":[ {"option":"function","values":[1,[4,7]]},
A list (and not just a single-type list, but a list that mixes scalar and sublist),
{"option":"device-number","values":31},
vs. a scalar. Why not a one-element array?
It was just to keep the representation as compact as possible, in the common case of single-value sets. Probably we can drop that feature as it saves only 2 bytes in the JSON representation.
{"option":"bus","values":"pcie.0"}], "opts-complete":true}
I planned to use QAPI alternates to model/document that in the schema, but it would require implementing a few missing features in QAPI alternate support.
Yeah, I can see how existing QAPI alternates do not yet support arrays, which becomes important to your representation. Do you need help getting the QAPI generator improved to support a particular feature that you found to be lacking?
I think the lack of support for lists on alternates was the main obstacle. Probably we would also need to remove the restriction against alternates with ambiguous string representations, to allow a list/number/string/bool alternate to be defined. Being able to set constraints on the number of elements of a list would be nice to have, but not required. -- Eduardo
participants (2)
-
Eduardo Habkost -
Eric Blake