$subject says all. First cut.
It's a pure UAS (usb attached scsi) emulation, without BOT (bulk-only
transport) compatibility. If your guest can't handle it use usb-storage
instead.
The emulation works like any other scsi hba emulation (eps, lsi, virtio,
megasas, ...). It provides just the HBA where you can attach scsi
devices as you like using '-device'. A single scsi target with up to
256 luns is supported.
For now only usb 2.0 transport is supported. This will change in the
future though as I plan to use this as playground when codeing up &
testing usb 3.0 transport and streams support in the qemu usb core and
the xhci emulation.
No migration support yet. I'm planning to add usb 3.0 support first as
this probably requires saving additional state.
Special thanks go to Paolo for bringing the qemu scsi emulation into
shape, so this can be added nicely without having to touch a single line
of scsi code.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
* quintela/migration-anthony-v2:
Maintain the number of dirty pages
dirty bitmap: abstract its use
Exit loop if we have been there too long
Only calculate expected_time for stage 2
Only TCG needs TLB handling
No need to iterate if we already are over the limit
Add tracepoints for savevm section start/end
Add spent time for migration
Add migration_end function
Add debugging infrastructure
Add save_block_hdr function
Add MigrationParams structure
Add missing check for host_from_stream_offset return value for RAM_SAVE_FLAG_PAGE
* kraxel/usb.55:
usb-host: add trace events for iso xfers
usb: fix interface initialization
usb: split endpoint init and reset
usb-redir: Correctly handle the usb_redir_babble usbredir status
ehci: Kick async schedule on wakeup in the non companion case
usb-ehci: Fix an assert whenever isoc transfers are used
ehci: don't flush cache on doorbell rings.
ehci: fix td writeback
ehci: fix ehci_qh_do_overlay
Replace iso transfer fprintf's with trace points. Also rename existing
tracepoints so they all match usb_host_iso_*.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This patch adds an emulation for the LSI Megaraid SAS 8708EM2 HBA.
I've tested it to work with Linux, Windows Vista, and Windows7.
Signed-off-by: Hannes Reinecke <hare@suse.de>
[ Squashed trivial changes from Andreas Faerber, rebased over IOMMU
and QBus changes - Paolo ]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This allows to know how long each section takes to save.
An awk script like this tells us sections that takes more that 10ms
$1 ~ /savevm_state_iterate_end/ {
/* Print savevm_section_end line when > 10ms duration */
if ($2 > 10000) {
printf("%s times_missing=%u\n", $0, times_missing++);
}
}
Signed-off-by: Juan Quintela <quintela@redhat.com>
fix ws tracepoints
Signed-off-by: Juan Quintela <quintela@redhat.com>
Allow certain event types to be rate limited to avoid flooding
monitor clients. The monitor_protocol_event() method is changed
such that instead of immediately emitting the event to Monitor
instances, it will call a new monitor_protocol_event_queue()
method.
This will check to see if the rate limit for the event has been
exceeded, and if so schedule a timer to wakeup at the end of the
rate limit period. If further events arrive before the timer fires,
the previously queued event will be discarded in favour of the new
event. The event will eventually be emitted when the timer fires.
This logic is applied to RTC_CHANGE, BALLOON_CHANGE & WATCHDOG
events, since the data associated with these events is stateless
* monitor.c: Add support for rate limiting
* monitor.h: Define monitor_global_init for one-time setup tasks
* vl.c: Invoke monitor_global_init
* trace-events: Add hooks for monitor event tracing
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Add a separate EHCIPacket struct and move fields over from EHCIQueue.
Preparing for supporting multiple packets per queue being in flight at
the same time. No functional changes yet.
Fix some codestyle issues along the way.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
uhci_process_frame() can be invoked multiple times per frame, so
accounting usb bandwith in a local variable doesn't fly, use a variable
in UHCIState instead. Also check the limit more frequently.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This allows using LUNs bigger than 2TB. Keep using READ10 for other
device types such as MMC.
Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
The resulting stp file fails to load because of an unresolvable probe.
Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This patch carries a complete rewrite of the usb descriptor parser.
Changes / improvements:
* We are using the USBDescriptor struct instead of hard-coded offsets
now to access descriptor data.
* (debug) printfs are all gone, tracepoints have been added instead.
* We don't try (and fail) to skip over unneeded descriptors. We parse
them all one by one. We keep track of which configuration, interface
and altsetting we are looking at and use this information to figure
which desciptors are in use and which we can ignore.
* On parse errors we clear all endpoint information, which will
disallow any communication with the device, except control endpoint
messages. This makes sure we don't end up with a silly device state
where half of the endpoints got enabled and the other half was left
disabled.
* Some sanity checks have been added.
The new parser is more robust and also leaves complete device
information in the trace log if you enable the ush_host_parse_*
tracepoints.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Add pointer to USBPacket to all tracepoints tracking requests to make it
easier to identify them when multiple requests are in flight.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
dprint is still used for qxl_init_common one time prints.
also switched parts of spice-display.c over, mainly all the callbacks to
spice server.
All qxl device trace events start with the qxl device id.
Signed-off-by: Alon Levy <alevy@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Add a new function to check whenever the packet state is as expected,
log more informations in case it isn't.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reorganize usb source files. Create a new hw/usb/ directory and move
all usb source code to that place. Also make filenames a bit more
descriptive. Host adapters are prefixed with "hch-" now, usb device
emulations are prefixed with "dev-". Fixup paths Makefile and include
paths to make it compile. No code changes.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
* kwolf/for-anthony:
test-coroutine: add performance test for nesting
coroutine: adding configure option for sigaltstack coroutine backend
coroutine: adding configure choose mechanism for coroutine backend
coroutine: adding sigaltstack method (.c source)
qcow2: Reduce number of I/O requests
qcow2: Add qcow2_alloc_clusters_at()
qcow2: Factor out count_cow_clusters
qmp: convert blockdev-snapshot-sync to a wrapper around transactions
add mode field to blockdev-snapshot-sync transaction item
rename blockdev-group-snapshot-sync
qapi: complete implementation of unions
use QSIMPLEQ_FOREACH_SAFE when freeing list elements
Add 'make check-block'
make check: Add qemu-iotests subset
qemu-iotests: Mark some tests as quick
qcow2: Add error messages in qcow2_truncate
block: handle -EBUSY in bdrv_commit_all()
qcow2: Add some tracing
qed: do not evict in-use L2 table cache entries
Group snapshot: Fix format name for backing file
If the first part of a write request is allocated, but the second isn't
and it can be allocated so that the resulting area is contiguous, handle
it at once. This is a common case for sequential writes.
After this patch, alloc_cluster_offset() only checks if the clusters are
already allocated or how many new clusters can be allocated contigouosly.
The actual cluster allocation is split off into a new function
do_alloc_cluster_offset().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Per-request attributes like read/write are currently implemented as bool
fields in the QEDAIOCB struct. This becomes unwiedly as the number of
attributes grows. For example, the qed_aio_setup() function would have
to take multiple bool arguments and at call sites it would be hard to
distinguish the meaning of each bool.
Instead use a flags field with bitmask constants. This will be used
when zero write support is added.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The ability to zero regions of an image file is a useful primitive for
higher-level features such as image streaming or zero write detection.
Image formats may support an optimized metadata representation instead
of writing zeroes into the image file. This allows zero writes to be
potentially faster than regular write operations and also preserve
sparseness of the image file.
The .bdrv_co_write_zeroes() interface should be implemented by block
drivers that wish to provide efficient zeroing.
Note that this operation is different from the discard operation, which
may leave the contents of the region indeterminate. That means
discarded blocks are not guaranteed to contain zeroes and may contain
junk data instead.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch implements the RX channel of GRLIB UART with a FIFO to
improve data rate.
Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
There already exists a virtio_blk_handle_write trace event as well as
completion events. Add the virtio_blk_handle_read event so it's easy to
trace virtio-blk requests for both read and write operations.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add block_job_cancel, which stops an active block streaming operation.
When the operation has been cancelled the new BLOCK_JOB_CANCELLED event
is emitted.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Acked-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add the block_stream command, which starts copy backing file contents
into the image file. Also add the BLOCK_JOB_COMPLETED QMP event which
is emitted when image streaming completes. Later patches add control
over the background copy speed, cancelation, and querying running
streaming operations.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Acked-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Previously copy-on-read could only be enabled for all requests to a
block device. This means requests coming from the guest as well as
QEMU's internal requests would perform copy-on-read when enabled.
For image streaming we want to support finer-grained behavior than just
populating the image file from its backing image. Image streaming
supports partial streaming where a common backing image is preserved.
In this case guest requests should not perform copy-on-read because they
would indiscriminately copy data which should be left in a backing image
from the backing chain.
Introduce a per-request flag for copy-on-read so that a block device can
process both regular and copy-on-read requests. Overlapping reads and
writes still need to be serialized for correctness when copy-on-read is
happening, so add an in-flight reference count to track this.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* qemu-kvm/uq/master:
kvm: Activate in-kernel irqchip support
kvm: x86: Add user space part for in-kernel IOAPIC
kvm: x86: Add user space part for in-kernel i8259
kvm: x86: Add user space part for in-kernel APIC
kvm: x86: Establish IRQ0 override control
kvm: Introduce core services for in-kernel irqchip support
memory: Introduce memory_region_init_reservation
ioapic: Factor out base class for KVM reuse
ioapic: Drop post-load irr initialization
i8259: Factor out base class for KVM reuse
i8259: Completely privatize PicState
apic: Open-code timer save/restore
apic: Factor out base class for KVM reuse
apic: Introduce apic_report_irq_delivered
apic: Inject external NMI events via LINT1
apic: Stop timer on reset
kvm: Move kvmclock into hw/kvm folder
msi: Generalize msix_supported to msi_supported
hyper-v: initialize Hyper-V CPUID leaves.
hyper-v: introduce Hyper-V support infrastructure.
Conflicts:
Makefile.target
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
* qemu-kvm/memory/page_desc: (22 commits)
Remove cpu_get_physical_page_desc()
sparc: avoid cpu_get_physical_page_desc()
virtio-balloon: avoid cpu_get_physical_page_desc()
vhost: avoid cpu_get_physical_page_desc()
kvm: avoid cpu_get_physical_page_desc()
memory: remove CPUPhysMemoryClient
xen: convert to MemoryListener API
memory: temporarily add memory_region_get_ram_addr()
xen, vga: add API for registering the framebuffer
vhost: convert to MemoryListener API
kvm: convert to MemoryListener API
kvm: switch kvm slots to use host virtual address instead of ram_addr_t
memory: add API for observing updates to the physical memory map
memory: replace cpu_physical_sync_dirty_bitmap() with a memory API
framebuffer: drop use of cpu_physical_sync_dirty_bitmap()
loader: remove calls to cpu_get_physical_page_desc()
framebuffer: drop use of cpu_get_physical_page_desc()
memory: introduce memory_region_find()
memory: add memory_region_is_logging()
memory: add memory_region_is_rom()
...
Initially done with the following semantic patch:
@ rule1 @
expression E;
statement S;
@@
E =
(
bdrv_aio_readv
| bdrv_aio_writev
| bdrv_aio_flush
| bdrv_aio_discard
| bdrv_aio_ioctl
)
(...);
(
- if (E == NULL) { ... }
|
- if (E)
{ <... S ...> }
)
which however missed the occurrence in block/blkverify.c
(as it should have done), and left behind some unused
variables.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
this patch fix multiple issues with VirtFS tracing.
a) Add tracepoint to the correct code path. We handle error in complete_pdu
b) Fix indentation in python script
c) Fix variable naming issue in python script
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Otherwise, if cancellation is "faked" by the AIO layer and goes
through qemu_aio_flush, the whole request is completed synchronously
during scsi_req_cancel.
Using the enqueued flag would work here, but not in the next patches,
so I'm introducing a new io_canceled flag. That's because scsi_req_data
is a synchronous callback and the enqueued flag might be reset by the
time it returns. scsi-disk cannot unref the request until after calling
scsi_req_data.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This provides built-in support for iSCSI to QEMU.
This has the advantage that the iSCSI devices need not be made visible to the host, which is useful if you have very many virtual machines and very many iscsi devices.
It also has the benefit that non-root users of QEMU can access iSCSI devices across the network without requiring root privilege on the host.
This driver interfaces with the multiplatform posix library for iscsi initiator/client access to iscsi devices hosted at
git://github.com/sahlberg/libiscsi.git
The patch adds the driver to interface with the iscsi library.
It also updated the configure script to
* by default, probe is libiscsi is available and if so, build
qemu against libiscsi.
* --enable-libiscsi
Force a build against libiscsi. If libiscsi is not available
the build will fail.
* --disable-libiscsi
Do not link against libiscsi, even if it is available.
When linked with libiscsi, qemu gains support to access iscsi resources such as disks and cdrom directly, without having to make the devices visible to the host.
You can specify devices using a iscsi url of the form :
iscsi://[<username>[:<password>@]]<host>[:<port]/<target-iqn-name>/<lun>
When using authentication, the password can optionally be set with
LIBISCSI_CHAP_PASSWORD="password" to avoid it showing up in the process list
Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This similarly adds support for coroutine and asynchronous discard.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Commit c572f23a3e added trace events
with mismatching format string and arguments.
gcc reports these errors:
In file included from trace.c:2:0:
trace.h: In function ‘trace_v9fs_attach’:
trace.h:2850:9: error: too many arguments for format [-Werror=format-extra-args]
trace.h: In function ‘trace_v9fs_wstat’:
trace.h:3039:9: error: too many arguments for format [-Werror=format-extra-args]
trace.h: In function ‘trace_v9fs_mkdir’:
trace.h:3088:9: error: too many arguments for format [-Werror=format-extra-args]
trace.h: In function ‘trace_v9fs_mkdir_return’:
trace.h:3095:9: error: too many arguments for format [-Werror=format-extra-args]
Fix the format strings and also use %u instead of %d for unsigned values
in the changed strings. There are more minor errors of this kind
which I did not fix because that would make the review more difficult.
v2: Fixed position of } for v9fs_mkdir_return.
Cc: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This is OpenCores Ethernet MAC + subset of National Semiconductors
DP83838C PHY.
OpenCores Ethernet MAC project: http://opencores.org/project,ethmac
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Plan is to replace the existing debug infrastructure with Qemu tracing
infrastructure so that user can dynamically enable/disable trace events and
therefore a meaningful trace log can be generated which can be further
filtered using an analysis script.
Note: Because of current simpletrace limitations, the trace events are
logging at max 6 args, however, once the more args are supported, we can
change trace events to log more info as well. Also, This initial patch only
provides a replacement for existing debug infra. More trace events to be
added later for newly added handlers and sub-routines.
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
* 'for-upstream' of git://git.serverraum.org/git/mw/qemu-lm32:
milkymist: new interrupt map
milkymist_uart: support new core version
lm32: add missing qemu_init_vcpu() call
It is useful to know the BlockDriverState as well as the
sector_num/nb_sectors of an emulated .bdrv_co_*() request.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Add trace events for handle_qmp_command(), which dispatches qmp
commands, and monitor_protocol_emitter(), which produces the reply to a
qmp command.
Also remove duplicate #include "trace/control.h".
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
bdrv_open_common() is a useful point to trace since it reveals the
filename and block driver for a given BlockDriverState.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
The virtio device lifecycle can be observed by looking at the sequence
of set status operations. This is especially important for catching the
reset operation (status value 0), which resets the device and all
virtqueues.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Now that format strings can end in a PRI*64 macro, remove the
workarounds from the trace-events file.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
There is no need to put a newline in trace event format strings. The
backend may use the format string within some context and takes care of
how to display the event. The stderr backend automatically appends "\n"
whereas the ust backend does not want a newline at all.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This patch makes qemu assign a port when creating the device, not when
attaching it. For most usb devices this isn't a noticable difference
because they are in attached state all the time.
The change affects usb-host devices which live in detached state while
the real device is unplugged from the host. They have a fixed port
assigned all the time now instead of getting grabbing one on attach and
releasing it at detach, i.e. they stop floating around at the usb bus.
The change also allows to simplify usb-hub. It doesn't need the
handle_attach() callback any more to configure the downstream ports.
This can be done at device initialitation time now. The changed
initialization order (first grab upstream port, then register downstream
ports) also fixes some icky corner cases. For example it is not possible
any more to plug the hub into one of its own downstream ports.
The usb host adapters must care too. USBPort->dev being non-NULL
doesn't imply any more the device is in attached state. The host
adapters must additionally check the USBPort->dev->attached flag.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This patch adds code to do minimal siTD handling, which is basically
just following the next pointer. This is good enougth to handle the
inactive siTDs used by FreeBSD. Active siTDs are skipped too as we
don't have split transfer support in qemu, additionally a warning is
printed.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
When configured to pass through a specific host port (using hostbus and
hostport properties), try to claim the port if supported by the kernel.
That will avoid any kernel drivers binding to devices plugged into that
port. It will not stop any userspace apps (such as usb_modeswitch)
access the device via usbfs though.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Add a bunch of trace points to usb-linux.c Drop a bunch of DPRINTK's in
favor of the trace points. Also cleanup error reporting a bit while being
at it.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Given that all events with programmatically-controlled state are disabled by
default, we can delete the "disable" property from all events.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Note that this refers to the backend-specific state (whether the output must be
generated), not the event "disabled" property (which always uses the "nop"
backend).
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Polarity of external interrupts needs to be handled in the IOAPIC.
Passing it to the APIC is pointless. So remove all these arguments.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Can be useful when debugging the device scan phase.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
With this patch, sense data is stored in the generic data structures
for SCSI devices and requests. The SCSI layer takes care of storing
sense data in the SCSIDevice for the subsequent REQUEST SENSE command.
At the same time, get_sense is removed and scsi_req_get_sense can use
an entirely generic implementation.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
In order to be able to call bdrv_co_readv/writev for drivers that don't
implement the functions natively, add an emulation that uses the AIO functions
to implement them.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add new block driver callbacks bdrv_co_readv/writev, which work on a
QEMUIOVector like bdrv_aio_*, but don't need a callback. The function may only
be called inside a coroutine, so a block driver implementing this interface can
yield instead of blocking during I/O.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Asynchronous code is becoming very complex. At the same time
synchronous code is growing because it is convenient to write.
Sometimes duplicate code paths are even added, one synchronous and the
other asynchronous. This patch introduces coroutines which allow code
that looks synchronous but is asynchronous under the covers.
A coroutine has its own stack and is therefore able to preserve state
across blocking operations, which traditionally require callback
functions and manual marshalling of parameters.
Creating and starting a coroutine is easy:
coroutine = qemu_coroutine_create(my_coroutine);
qemu_coroutine_enter(coroutine, my_data);
The coroutine then executes until it returns or yields:
void coroutine_fn my_coroutine(void *opaque) {
MyData *my_data = opaque;
/* do some work */
qemu_coroutine_yield();
/* do some more work */
}
Yielding switches control back to the caller of qemu_coroutine_enter().
This is typically used to switch back to the main thread's event loop
after issuing an asynchronous I/O request. The request callback will
then invoke qemu_coroutine_enter() once more to switch back to the
coroutine.
Note that if coroutines are used only from threads which hold the global
mutex they will never execute concurrently. This makes programming with
coroutines easier than with threads. Race conditions cannot occur since
only one coroutine may be active at any time. Other coroutines can only
run across yield.
This coroutines implementation is based on the gtk-vnc implementation
written by Anthony Liguori <anthony@codemonkey.ws> but it has been
significantly rewritten by Kevin Wolf <kwolf@redhat.com> to use
setjmp()/longjmp() instead of the more expensive swapcontext() and by
Paolo Bonzini <pbonzini@redhat.com> for Windows Fibers support.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
"next" is reserved in systemtap thus using this as a
trace parameter name causes trouble when trying to trace
with systemtap.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
