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* [RFC PATCH] Update virtio spec for virtio-ccw.
@ 2012-08-07 14:52 ` Cornelia Huck
  0 siblings, 0 replies; 4+ messages in thread
From: Cornelia Huck @ 2012-08-07 14:52 UTC (permalink / raw)
  To: KVM, linux-s390, qemu-devel
  Cc: Avi Kivity, Marcelo Tosatti, Anthony Liguori, Rusty Russell,
	Christian Borntraeger, Carsten Otte, Alexander Graf,
	Heiko Carstens, Martin Schwidefsky, Sebastian Ott

Hi,

here's an update to the virtio spec describing the basics of
the virtio-ccw mechanism.

Cornelia Huck (1):
  virtio-spec: Add virtio-ccw spec.

 virtio-spec.lyx |  433 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 433 insertions(+), 0 deletions(-)

-- 
1.7.5.4

^ permalink raw reply	[flat|nested] 4+ messages in thread
* [Qemu-devel] [RFC PATCH] Update virtio spec for virtio-ccw.
@ 2012-08-07 14:52 ` Cornelia Huck
  0 siblings, 0 replies; 4+ messages in thread
From: Cornelia Huck @ 2012-08-07 14:52 UTC (permalink / raw)
  To: KVM, linux-s390, qemu-devel
  Cc: Carsten Otte, Anthony Liguori, Rusty Russell, Sebastian Ott,
	Marcelo Tosatti, Heiko Carstens, Alexander Graf,
	Christian Borntraeger, Avi Kivity, Martin Schwidefsky

Hi,

here's an update to the virtio spec describing the basics of
the virtio-ccw mechanism.

Cornelia Huck (1):
  virtio-spec: Add virtio-ccw spec.

 virtio-spec.lyx |  433 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 433 insertions(+), 0 deletions(-)

-- 
1.7.5.4

^ permalink raw reply	[flat|nested] 4+ messages in thread
* [PATCH] virtio-spec: Add virtio-ccw spec.
  2012-08-07 14:52 ` [Qemu-devel] " Cornelia Huck
@ 2012-08-07 14:52   ` Cornelia Huck
  -1 siblings, 0 replies; 4+ messages in thread
From: Cornelia Huck @ 2012-08-07 14:52 UTC (permalink / raw)
  To: KVM, linux-s390, qemu-devel
  Cc: Avi Kivity, Marcelo Tosatti, Anthony Liguori, Rusty Russell,
	Christian Borntraeger, Carsten Otte, Alexander Graf,
	Heiko Carstens, Martin Schwidefsky, Sebastian Ott

Add specifications for the new s390 specific virtio-ccw transport.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 virtio-spec.lyx |  433 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 433 insertions(+), 0 deletions(-)

diff --git a/virtio-spec.lyx b/virtio-spec.lyx
index 7a073f4..5223380 100644
--- a/virtio-spec.lyx
+++ b/virtio-spec.lyx
@@ -57,6 +57,7 @@
 \html_css_as_file 0
 \html_be_strict false
 \author -608949062 "Rusty Russell,,," 
+\author -385801441 "Cornelia Huck" cornelia.huck@de.ibm.com
 \author 1531152142 "Paolo Bonzini,,," 
 \end_header
 
@@ -9350,6 +9351,438 @@ tatus register description is asserted.
  After the interrupt is handled, the driver must acknowledge it by writing
  a bit mask corresponding to the serviced interrupt to the InterruptACK
  register.
+\change_inserted -385801441 1343732742
+
+\end_layout
+
+\begin_layout Chapter*
+
+\change_inserted -385801441 1343732726
+Appendix Y: virtio-ccw
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+S/390 based virtual machines support neither PCI nor MMIO, so a different
+ transport is needed there.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The old s390-virtio mechanism used a special page mapped above the guest's
+ memory and several diagnose calls (hypercalls); it does have some drawbacks,
+ however, like a rather limited number of devices and very restricted hotplug
+ support.
+ Moreover, device discovery and operation differ from other environments
+ on the S/390 platform.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+virtio-ccw uses the standard channel I/O based mechanism used for the majority
+ of devices on S/390.
+ A virtual channel device with a special control unit type acts as proxy
+ to the virtio device (similar to the way virtio-pci uses a PCI device)
+ and configuration and operation of the virtio device is accomplished (mostly)
+ via channel commands.
+ This means virtio devices are discoverable via standard operating system
+ algorithms, and adding virtio support is mainly a question of supporting
+ a new control unit type.
+\end_layout
+
+\begin_layout Subsection*
+
+\change_inserted -385801441 1343732726
+Basic Concepts
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732817
+As a proxy device, virtio-ccw uses a channel-attached I/O control unit with
+ a special control unit type (0x3832) and a control unit model corresponding
+ to the attached virtio device's subsystem device ID, accessed via a virtual
+ I/O subchannel and a virtual channel path of type 0x32.
+ This proxy device is discoverable via normal channel subsystem device discorver
+y (usually a STORE SUBCHANNEL loop) and answers to the basic channel commands,
+ most importantly SENSE ID.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+In addition to the basic channel commands, virtio-ccw defines a set of channel
+ commands related to configuration and operation of virtio:
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+\begin_inset listings
+inline false
+status open
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_SET_VQ 0x13
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_VDEV_RESET 0x33
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_SET_IND 0x43
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_READ_FEAT 0x12
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_WRITE_FEAT 0x11
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_READ_CONF 0x22 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_WRITE_CONF 0x21
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_WRITE_STATUS 0x31
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_READ_VQ_CONF 0x32
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection*
+
+\change_inserted -385801441 1343732726
+Device Initialization
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+virtio-ccw uses several channel commands to set up a device.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Configuring a Virtqueue
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+CCW_CMD_READ_VQ_CONF is issued by the guest to obtain information about
+ a queue.
+ It uses the following structure for communicating:
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+\begin_inset listings
+inline false
+status open
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+struct vq_config_block { 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint16_t index; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint16_t num; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+} __attribute__ ((packed));
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The number of buffers for queue 
+\family typewriter
+index
+\family default
+ is returned in 
+\family typewriter
+num
+\family default
+.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+Afterwards, CCW_CMD_SET_VQ is issued by the guest to inform the host about
+ the location used for its queue.
+ The transmitted structure is
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+\begin_inset listings
+inline false
+status open
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+struct vq_info_block { 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint64_t queue; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint16_t num; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+} __attribute__ ((packed)); 
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+
+\family typewriter
+queue
+\family default
+ contains the guest address for queue 
+\family typewriter
+num
+\family default
+.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Communicating Status Information
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The guest can change the status of a device via the CCW_CMD_WRITE_STATUS
+ command, which transmits an 8 bit status value.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Handling Device Features
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+Features are a 32 bit value.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The guest may obtain the host's device feature set via the CCW_CMD_READ_FEAT
+ command, which provides a guest address for the host to store the features
+ to.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For communicating its device features to the host, the guest may use the
+ CCW_CMD_WRITE_FEAT command pointing to a guest address where the guest
+ features can be obtained.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Device Configuration
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The device's configuration space is located in host memory.
+ It is the same size as the standard PCI configuration space.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+To obtain information from the configuration space, the guest may use CCW_CMD_RE
+AD_CONF, specifying the guest memory for the host to write to.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For changing configuration information, the guest may use CCW_CMD_WRITE_CONF,
+ specifying the guest memory for the host to read from.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+In both cases, the complete configuration space is transmitted.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Setting Up Indicators
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+To communicate the location of the indicator bits for host->guest notification,
+ the guest uses the CCW_CMD_SET_IND command which sends the guest address
+ of the indicators in a 64 bit value.
+\end_layout
+
+\begin_layout Subsection*
+
+\change_inserted -385801441 1343732726
+Device Operation
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Host->Guest Notification
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For notifying the guest of virtqueue buffers, the host sets the corresponding
+ bit in the guest-provided indicators.
+ If an interrupt is not already pending for the subchannel, the host generates
+ an unsolicited I/O interrupt.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Guest->Host Notification
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For notifying the host of virtqueue buffers, the guest unfortunately can't
+ use a channel command (the asynchronous characteristics of channel I/O
+ interact badly with the host block I/O backend).
+ Instead, it uses a diagnose 0x500 call with subcode 3 specifying the queue.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Early printk for Virtio Consoles
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For the early printk mechanism, diagnose 0x500 with subcode 0 is used.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Resetting Devices
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+In order to reset a device, a guest may send the CCW_CMD_VDEV_RESET command.
+\change_unchanged
+
 \end_layout
 
 \end_deeper
-- 
1.7.5.4

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [Qemu-devel] [PATCH] virtio-spec: Add virtio-ccw spec.
@ 2012-08-07 14:52   ` Cornelia Huck
  0 siblings, 0 replies; 4+ messages in thread
From: Cornelia Huck @ 2012-08-07 14:52 UTC (permalink / raw)
  To: KVM, linux-s390, qemu-devel
  Cc: Carsten Otte, Anthony Liguori, Rusty Russell, Sebastian Ott,
	Marcelo Tosatti, Heiko Carstens, Alexander Graf,
	Christian Borntraeger, Avi Kivity, Martin Schwidefsky

Add specifications for the new s390 specific virtio-ccw transport.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 virtio-spec.lyx |  433 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 433 insertions(+), 0 deletions(-)

diff --git a/virtio-spec.lyx b/virtio-spec.lyx
index 7a073f4..5223380 100644
--- a/virtio-spec.lyx
+++ b/virtio-spec.lyx
@@ -57,6 +57,7 @@
 \html_css_as_file 0
 \html_be_strict false
 \author -608949062 "Rusty Russell,,," 
+\author -385801441 "Cornelia Huck" cornelia.huck@de.ibm.com
 \author 1531152142 "Paolo Bonzini,,," 
 \end_header
 
@@ -9350,6 +9351,438 @@ tatus register description is asserted.
  After the interrupt is handled, the driver must acknowledge it by writing
  a bit mask corresponding to the serviced interrupt to the InterruptACK
  register.
+\change_inserted -385801441 1343732742
+
+\end_layout
+
+\begin_layout Chapter*
+
+\change_inserted -385801441 1343732726
+Appendix Y: virtio-ccw
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+S/390 based virtual machines support neither PCI nor MMIO, so a different
+ transport is needed there.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The old s390-virtio mechanism used a special page mapped above the guest's
+ memory and several diagnose calls (hypercalls); it does have some drawbacks,
+ however, like a rather limited number of devices and very restricted hotplug
+ support.
+ Moreover, device discovery and operation differ from other environments
+ on the S/390 platform.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+virtio-ccw uses the standard channel I/O based mechanism used for the majority
+ of devices on S/390.
+ A virtual channel device with a special control unit type acts as proxy
+ to the virtio device (similar to the way virtio-pci uses a PCI device)
+ and configuration and operation of the virtio device is accomplished (mostly)
+ via channel commands.
+ This means virtio devices are discoverable via standard operating system
+ algorithms, and adding virtio support is mainly a question of supporting
+ a new control unit type.
+\end_layout
+
+\begin_layout Subsection*
+
+\change_inserted -385801441 1343732726
+Basic Concepts
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732817
+As a proxy device, virtio-ccw uses a channel-attached I/O control unit with
+ a special control unit type (0x3832) and a control unit model corresponding
+ to the attached virtio device's subsystem device ID, accessed via a virtual
+ I/O subchannel and a virtual channel path of type 0x32.
+ This proxy device is discoverable via normal channel subsystem device discorver
+y (usually a STORE SUBCHANNEL loop) and answers to the basic channel commands,
+ most importantly SENSE ID.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+In addition to the basic channel commands, virtio-ccw defines a set of channel
+ commands related to configuration and operation of virtio:
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+\begin_inset listings
+inline false
+status open
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_SET_VQ 0x13
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_VDEV_RESET 0x33
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_SET_IND 0x43
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_READ_FEAT 0x12
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_WRITE_FEAT 0x11
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_READ_CONF 0x22 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_WRITE_CONF 0x21
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_WRITE_STATUS 0x31
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+#define CCW_CMD_READ_VQ_CONF 0x32
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection*
+
+\change_inserted -385801441 1343732726
+Device Initialization
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+virtio-ccw uses several channel commands to set up a device.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Configuring a Virtqueue
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+CCW_CMD_READ_VQ_CONF is issued by the guest to obtain information about
+ a queue.
+ It uses the following structure for communicating:
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+\begin_inset listings
+inline false
+status open
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+struct vq_config_block { 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint16_t index; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint16_t num; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+} __attribute__ ((packed));
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The number of buffers for queue 
+\family typewriter
+index
+\family default
+ is returned in 
+\family typewriter
+num
+\family default
+.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+Afterwards, CCW_CMD_SET_VQ is issued by the guest to inform the host about
+ the location used for its queue.
+ The transmitted structure is
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+\begin_inset listings
+inline false
+status open
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+struct vq_info_block { 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint64_t queue; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+	uint16_t num; 
+\end_layout
+
+\begin_layout LyX-Code
+
+\change_inserted -385801441 1343732726
+
+} __attribute__ ((packed)); 
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+
+\family typewriter
+queue
+\family default
+ contains the guest address for queue 
+\family typewriter
+num
+\family default
+.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Communicating Status Information
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The guest can change the status of a device via the CCW_CMD_WRITE_STATUS
+ command, which transmits an 8 bit status value.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Handling Device Features
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+Features are a 32 bit value.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The guest may obtain the host's device feature set via the CCW_CMD_READ_FEAT
+ command, which provides a guest address for the host to store the features
+ to.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For communicating its device features to the host, the guest may use the
+ CCW_CMD_WRITE_FEAT command pointing to a guest address where the guest
+ features can be obtained.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Device Configuration
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+The device's configuration space is located in host memory.
+ It is the same size as the standard PCI configuration space.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+To obtain information from the configuration space, the guest may use CCW_CMD_RE
+AD_CONF, specifying the guest memory for the host to write to.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For changing configuration information, the guest may use CCW_CMD_WRITE_CONF,
+ specifying the guest memory for the host to read from.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+In both cases, the complete configuration space is transmitted.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Setting Up Indicators
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+To communicate the location of the indicator bits for host->guest notification,
+ the guest uses the CCW_CMD_SET_IND command which sends the guest address
+ of the indicators in a 64 bit value.
+\end_layout
+
+\begin_layout Subsection*
+
+\change_inserted -385801441 1343732726
+Device Operation
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Host->Guest Notification
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For notifying the guest of virtqueue buffers, the host sets the corresponding
+ bit in the guest-provided indicators.
+ If an interrupt is not already pending for the subchannel, the host generates
+ an unsolicited I/O interrupt.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Guest->Host Notification
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For notifying the host of virtqueue buffers, the guest unfortunately can't
+ use a channel command (the asynchronous characteristics of channel I/O
+ interact badly with the host block I/O backend).
+ Instead, it uses a diagnose 0x500 call with subcode 3 specifying the queue.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Early printk for Virtio Consoles
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+For the early printk mechanism, diagnose 0x500 with subcode 0 is used.
+\end_layout
+
+\begin_layout Subsubsection*
+
+\change_inserted -385801441 1343732726
+Resetting Devices
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted -385801441 1343732726
+In order to reset a device, a guest may send the CCW_CMD_VDEV_RESET command.
+\change_unchanged
+
 \end_layout
 
 \end_deeper
-- 
1.7.5.4

^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-08-07 14:53 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-08-07 14:52 [RFC PATCH] Update virtio spec for virtio-ccw Cornelia Huck
2012-08-07 14:52 ` [Qemu-devel] " Cornelia Huck
2012-08-07 14:52 ` [PATCH] virtio-spec: Add virtio-ccw spec Cornelia Huck
2012-08-07 14:52   ` [Qemu-devel] " Cornelia Huck

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