--- /dev/null
+
+Overview
+
+This document describes the driver set for Unisys Secure Partitioning (s-Par®).
+
+s-Par is firmware that provides hardware partitioning capabilities for
+splitting large-scale Intel x86 servers into multiple isolated
+partitions. s-Par provides a set of para-virtualized device drivers to
+allow guest partitions on the same server to share devices that would
+normally be unsharable; specifically, PCI network interfaces and host
+bus adapters that do not support shared access via SR-IOV. The shared
+device is owned and managed by a small, single-purpose service
+partition, which communicates with each guest partition sharing that
+device through an area of shared memory called a channel. Additional
+drivers provide support interfaces for communicating with s-Par
+services, logging and diagnostics, and accessing the Linux console
+from the s-Par user interface.
+
+The driver stack consists of a set of support modules, a set of bus
+modules, and a set of device driver modules. The support modules
+handle a number of common functions across each of the other
+drivers. The bus modules provide organization for the device driver
+modules, which provide the shared device functionality.
+
+These drivers are for the Unisys virtual PCI hardware model where the
+hypervisor need not intervene (other than normal interrupt handling)
+in the interactions between the client drivers and the virtual adapter
+firmware in the adapter service partition.
+
+Driver Descriptions
+
+Device Modules
+
+The modules in this section handle shared devices and the virtual
+buses required to support them. These modules use functions in and
+depend on the modules described in the support modules section.
+
+visorchipset
+
+The visorchipset module receives device creation and destruction
+events from the Command service partition of s-Par, as well as
+controlling registration of shared device drivers with the s-Par
+driver core. The events received are used to populate other s-Par
+modules with their assigned shared devices. Visorchipset is required
+for shared device drivers to function properly. Visorchipset also
+stores information for handling dump disk device creation during
+kdump.
+
+In operation, the visorchipset module processes device creation and
+destruction messages sent by s-Par's Command service partition through
+a channel. These messages result in creation (or destruction) of each
+virtual bus and virtual device. Each bus and device is also associated
+with a communication channel, which is used to communicate with one or
+more IO service partitions to perform device IO on behalf of the
+guest.
+
+virthba
+
+The virthba module provides access to a shared SCSI host bus adapter
+and one or more disk devices, by proxying SCSI commands between the
+guest and the service partition that owns the shared SCSI adapter,
+using a channel between the guest and the service partition. The disks
+that appear on the shared bus are defined by the s-Par configuration
+and enforced by the service partition, while the guest driver handles
+sending commands and handling responses. Each disk is shared as a
+whole to a guest. Sharing the bus adapter in this way provides
+resiliency; should the device encounter an error, only the service
+partition is rebooted, and the device is reinitialized. This allows
+guests to continue running and to recover from the error.
+
+virtnic
+
+The virtnic module provides a paravirtualized network interface to a
+guest by proxying buffer information between the guest and the service
+partition that owns the shared network interface, using a channel
+between the guest and the service partition. The connectivity of this
+interface with the shared interface and possibly other guest
+partitions is defined by the s-Par configuration and enforced by the
+service partition; the guest driver handles communication and link
+status.
+
+visorserial
+
+The visorserial module allows the console of the linux guest to be
+accessed via the s-Par console serial channel. It creates devices in
+/dev/visorserialclientX which behave like a serial terminal and are
+connected to the diagnostics system in s-Par. By assigning a getty to
+the terminal in the guest, a user could log into and access the guest
+from the s-Par diagnostics SWITCH RUN terminal.
+
+visorbus
+
+The visorbus module handles the bus functions for most functional
+drivers except visorserial, visordiag, virthba, and virtnic. It
+maintains the sysfs subtree /sys/devices/visorbus*/. It is responsible
+for device creation and destruction of the devices on its bus.
+
+visorclientbus
+
+The visorclientbus module forwards the bus functions for virthba, and
+virtnic to the virtpci driver.
+
+virtpci
+
+The virtpci module handles the bus functions for virthba, and virtnic.
+
+s-Par Integration Modules
+
+The modules in this section provide integration with s-Par guest
+partition services like diagnostics and remote desktop. These modules
+depend on functions in the modules described in the support modules
+section.
+
+visorvideoclient
+
+The visorvideoclient module provides functionality for video support
+for the Unisys s-Par Partition Desktop application. The guest OS must
+also have the UEFI GOP protocol enabled for the partition desktop to
+function. visorconinclient The visorconinclient module provides
+keyboard and mouse support for the Unisys s-Par Partition Desktop
+application.
+
+sparstop
+
+The sparstop module handles requests from the Unisys s-Par platform to
+shutdown the linux guest. It allows a program on the guest to perform
+clean-up functions on the guest before the guest is shut down or
+rebooted using ACPI.
+
+visordiag
+
+This driver provides the ability for the guest to write information
+into the s-Par diagnostics subsystem. It creates a set of devices
+named /dev/visordiag.X which can be written to by the guest to add
+text to the s-Par system log.
+
+Support Modules
+
+The modules described in this section provide functions and
+abstractions to support the modules described in the previous
+sections, to avoid having duplicated functionality.
+
+visornoop
+
+The visornoop module is a placeholder that responds to device
+create/destroy messages that are currently not in use by linux guests.
+
+visoruislib
+
+The visoruislib module is a support library, used to handle requests
+from virtpci.
+
+visorchannelstub
+
+The visorchannelstub module provides support routines for storing and
+retrieving data from a channel.
+
+visorchannel
+
+The visorchannel module is a support library that abstracts reading
+and writing a channel in memory.
+
+visorutil
+
+The visorutil module is a support library required by all other s-Par
+driver modules. Among its features it abstracts reading, writing, and
+manipulating a block of memory.
+
+Minimum Required Driver Set
+
+The drivers required to boot a Linux guest are visorchipset, visorbus,
+visorvideoclient, visorconinclient, visoruislib, visorchannelstub,
+visorchannel, and visorutil. The other drivers are required by the
+product configurations that are currently being marketed.
--- /dev/null
+ s-Par Proc Entries
+This document describes the proc entries created by the Unisys s-Par modules.
+
+Support Module Entries
+These entries are provided primarily for debugging.
+
+/proc/uislib/info: This entry contains debugging information for the
+uislib module, including bus information and memory usage.
+
+/proc/visorchipset/controlvm: This directory contains debugging
+entries for the controlvm channel used by visorchipset.
+
+/proc/uislib/platform: This entry is used to display the platform
+number this node is in the system. For some guests, this may be
+invalid.
+
+/proc/visorchipset/chipsetready: This entry is written to by scripts
+to signify that any user level activity has been completed before the
+guest can be considered running and is shown as running in the s-Par
+UI.
+
+Device Entries
+These entries provide status of the devices shared by a service partition.
+
+/proc/uislib/vbus: this is a directory containing entries for each
+virtual bus. Each numbered sub-directory contains an info entry, which
+describes the devices that appear on that bus.
+
+/proc/uislib/cycles_before_wait: This entry is used to tune
+performance, by setting the number of cycles we wait before going idle
+when in polling mode. A longer time will reduce message latency but
+spend more processing time polling.
+
+/proc/uislib/smart_wakeup: This entry is used to tune performance, by
+enabling or disabling smart wakeup.
+
+/proc/virthba/info: This entry contains debugging information for the
+virthba module, including interrupt information and memory usage.
+
+/proc/virthba/enable_ints: This entry controls interrupt use by the
+virthba module. Writing a 0 to this entry will disable interrupts.
+
+/proc/virtnic/info: This entry contains debugging information for the
+virtnic module, including interrupt information, send and receive
+counts, and other device information.
+
+/proc/virtnic/ethX: This is a directory containing entries for each
+virtual NIC. Each named subdirectory contains two entries,
+clientstring and zone.
+
+/proc/virtpci/info: This entry contains debugging information for the
+virtpci module, including virtual PCI bus information and device
+locations.
+
+/proc/virtnic/enable_ints: This entry controls interrupt use by the
+virtnic module. Writing a 0 to this entry will disable interrupts.
+
+Visorconinclient, visordiag, visornoop, visorserialclient, and
+visorvideoclient Entries
+
+The entries in proc for these modules all follow the same
+pattern. Each module has its own proc directory with the same name,
+e.g. visordiag presents a /proc/visordiag directory. Inside of the
+module's directory are a device directory, which contains one numbered
+directory for each device provided by that module. Each device has a
+diag entry that presents the device number and visorbus name for that
+device. The module directory also has a driver/diag entry, which
+reports the corresponding s-Par version number of the driver.
+
+Automated Installation Entries
+
+These entries are used to pass information between the s-Par platform
+and the Linux-based installation and recovery tool. These values are
+read/write, however, the guest can only reset them to 0, or report an
+error status through the installer entry. The values are only set via
+s-Par's firmware interface, to help prevent accidentally booting into
+the tool.
+
+/proc/visorchipset/boottotool: This entry instructs s-Par that the
+next reboot will launch the installation and recovery tool. If set to
+0, the next boot will happen according to the UEFI boot manager
+settings.
+
+/proc/visorchipset/toolaction: This entry indicates the installation
+and recovery tool mode requested for the next boot.
+
+/proc/visorchipset/installer: this entry is used by the installation
+and recovery tool to pass status and result information back to the
+s-Par firmware.
+
+/proc/visorchipset/partition: This directory contains the guest
+partition configuration data for each virtual bus, for use during
+installation and at runtime for s-Par service partitions.
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