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Index ¶
Constants ¶
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const ( InvalidDeviceID = DeviceID(0) NetworkDeviceID = DeviceID(1) BlockDeviceID = DeviceID(2) ConsoleDeviceID = DeviceID(3) SocketDeviceID = DeviceID(19) )
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const ( MagicValue = 0x74726976 // "virt" Version = 0x2 )
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const ( // FIndirectDesc (VIRTIO_F_INDIRECT_DESC) "indicates that the driver can use // descriptors with the VIRTQ_DESC_F_INDIRECT flag set, as described in 2.6.5.3 // Indirect Descriptors and 2.7.7 Indirect Flag: Scatter-Gather Support." FIndirectDesc = 1 << 28 // FEventIdx (VIRTIO_F_EVENT_IDX) "enables the used_event and the avail_event fields // as described in 2.6.7, 2.6.8 and 2.7.10." FEventIdx = 1 << 29 // FVersion1 (VIRTIO_F_VERSION_1) "indicates compliance with [the virtio] // specification, giving a simple way to detect legacy devices or drivers." FVersion1 = 1 << 32 // FAccessPlatform (VIRTIO_F_ACCESS_PLATFORM) "indicates that the device can be used // on a platform where device access to data in memory is limited and/or translated. // E.g. this is the case if the device can be located behind an IOMMU that translates // bus addresses from the device into physical addresses in memory, if the device can // be limited to only access certain memory addresses or if special commands such as a // cache flush can be needed to synchronise data in memory with the device. Whether // accesses are actually limited or translated is described by platform-specific // means. // // If this feature bit is set to 0, then the device has same access to memory // addresses supplied to it as the driver has. In particular, the device will always // use physical addresses matching addresses used by the driver (typically meaning // physical addresses used by the CPU) and not translated further, and can access any // address supplied to it by the driver. When clear, this overrides any platform- // specific description of whether device access is limited or translated in any way, // e.g. whether an IOMMU may be present." FAccessPlatform = 1 << 33 // FRingPacked (VIRTIO_F_RING_PACKED) "indicates support for the packed virtqueue // layout as described in 2.7 Packed Virtqueues." FRingPacked = 1 << 34 // FInOrder (VIRTIO_F_IN_ORDER) "indicates that all buffers are used by the device in // the same order in which they have been made available." FInOrder = 1 << 35 // FOrderPlatform (VIRTIO_F_ORDER_PLATFORM) "indicates that memory accesses by the // driver and the device are ordered in a way described by the platform. If this // feature bit is negotiated, the ordering in effect for any memory accesses by the // driver that need to be ordered in a specific way with respect to accesses by the // device is the one suitable for devices described by the platform. This implies that // the driver needs to use memory barriers suitable for devices described by the // platform; e.g. for the PCI transport in the case of hardware PCI devices. // // If this feature bit is not negotiated, then the device and driver are assumed to be // implemented in software, that is they can be assumed to run on identical CPUs in an // SMP configuration. Thus a weaker form of memory barriers is sufficient to yield // better performance." FOrderPlatform = 1 << 36 // FSRIOV (VIRTIO_F_SR_IOV) "indicates that the device supports Single Root I/O // Virtualization. Currently only PCI devices support this feature." FSRIOV = 1 << 37 // FNotificationData (VIRTIO_F_NOTIFICATION_DATA) "indicates that the driver passes // extra data (besides identifying the virtqueue) in its device notifications. See // 2.7.23 Driver notifications." FNotificationData = 1 << 38 // FNotifConfigData (VIRTIO_F_NOTIF_CONFIG_DATA) "indicates that the driver uses the // data provided by the device as a virtqueue identifier in available buffer // notifications. As mentioned in section 2.9, when the driver is required to send an // available buffer notification to the device, it sends the virtqueue number to be // notified. The method of delivering notifications is transport specific. With the // PCI transport, the device can optionally provide a per-virtqueue value for the // driver to use in driver notifications, instead of the virtqueue number. Some // devices may benefit from this flexibility by providing, for example, an internal // virtqueue identifier, or an internal offset related to the virtqueue number. // // This feature indicates the availability of such value. The definition of the data // to be provided in driver notification and the delivery method is transport // specific. For more details about driver notifications over PCI see 4.1.5.2." FNotifConfigData = 1 << 39 // FRingReset (VIRTIO_F_RING_RESET) "indicates that the driver can reset a queue // individually. See 2.6.1." FRingReset = 1 << 40 )
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const RequiredFeatures = FVersion1 | FRingPacked | FIndirectDesc | FEventIdx
RequiredFeatures are the feature bits negotiated for all virtio devices.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type BlockDevice ¶
type BlockDevice struct {
// ReadOnly forces the device to be read-only.
ReadOnly bool
// Storage is the backing storage for the device. Storage may also
// implement the io.WriterAt interface to enable writes.
Storage BlockStorage
}
BlockDevice configures a virtio block device.
func (BlockDevice) NewHandler ¶
func (cfg BlockDevice) NewHandler() (DeviceHandler, error)
type BlockStorage ¶
type BlockStorage interface {
io.ReaderAt
// Size returns the storage size in bytes.
Size() (int64, error)
}
BlockStorage is the basic interface to a block device's backing storage. It is read-only: To enable writes, storage types should also implement io.WriterAt.
type ConsoleDevice ¶
ConsoleDevice configures a virtio console device.
func (ConsoleDevice) NewHandler ¶
func (cfg ConsoleDevice) NewHandler() (DeviceHandler, error)
type DeviceConfig ¶
type DeviceConfig interface {
NewHandler() (DeviceHandler, error)
}
type DeviceHandler ¶
type DeviceHandler interface {
// GetType identifies the type of the device.
GetType() DeviceID
// GetFeatures returns additional feature bits supported by the device.
GetFeatures() uint64
// Ready is called after feature negotiation is complete.
Ready(negotiatedFeatures uint64) error
// QueueReady is called when a new virtqueue is available. The bus
// sends to the given notify channel when there are new buffers in
// the queue.
QueueReady(num int, q *virtq.Queue, notify <-chan struct{}) error
// ReadConfig reads the device configuration register at off into p.
ReadConfig(p []byte, off int) error
// Close is called when the system is shutting down.
Close() error
}
type FileStorage ¶
FileStorage is read-write block storage backed by a file.
func (*FileStorage) ReadAt ¶
func (fs *FileStorage) ReadAt(p []byte, off int64) (n int, err error)
ReadAt reads from the backing file.
func (*FileStorage) Size ¶
func (fs *FileStorage) Size() (int64, error)
Size stats the backing file and returns its size in bytes.
type HTTPStorage ¶
type HTTPStorage struct {
URL string
// Client is the HTTP client to use for requests.
// If nil, http.DefaultClient is used.
Client *http.Client
}
HTTP storage is read-only block storage backed by an HTTP URL. The server must support HEAD requests and GET requests with a Range header.
func (*HTTPStorage) ReadAt ¶
func (hs *HTTPStorage) ReadAt(p []byte, off int64) (n int, err error)
ReadAt gets the backing URL with a Range header generated from off and len(p).
func (*HTTPStorage) Size ¶
func (hs *HTTPStorage) Size() (int64, error)
Size sends a HEAD request to the backing URL and parses the Content-Length response header.
type MemStorage ¶
type MemStorage struct {
Bytes []byte
}
MemStorage is read-write block storage backed by a byte slice.
func (*MemStorage) ReadAt ¶
func (ms *MemStorage) ReadAt(p []byte, off int64) (n int, err error)
ReadAt copies from the backing slice at off into p.
func (*MemStorage) Size ¶
func (ms *MemStorage) Size() (int64, error)
Size returns the size of the backing slice in bytes.
Source Files
Directories
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| Path | Synopsis |
|---|---|
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Package mmio implements a virtio-mmio device bus.
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Package mmio implements a virtio-mmio device bus. |
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Package virtq partially implements packed virtqueues as described by the Virtual I/O Device (VIRTIO) Version 1.2 spec.
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Package virtq partially implements packed virtqueues as described by the Virtual I/O Device (VIRTIO) Version 1.2 spec. |
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