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Emilio G. Cota 37b995f6e7 target-i386: remove helper_lock() 
It's been superseded by the atomic helpers.

The use of the atomic helpers provides a significant performance and scalability
improvement. Below is the result of running the atomic_add-test microbenchmark with:
 $ x86_64-linux-user/qemu-x86_64 tests/atomic_add-bench -o 5000000 -r $r -n $n
, where $n is the number of threads and $r is the allowed range for the additions.

The scenarios measured are:
- atomic: implements x86' ADDL with the atomic_add helper (i.e. this patchset)
- cmpxchg: implement x86' ADDL with a TCG loop using the cmpxchg helper
- master: before this patchset

Results sorted in ascending range, i.e. descending degree of contention.
Y axis is Throughput in Mops/s. Tests are run on an AMD machine with 64
Opteron 6376 cores.

                atomic_add-bench: 5000000 ops/thread, [0,1] range

  25 ++---------+----------+---------+----------+----------+----------+---++
     + atomic +-E--+       +         +          +          +          +    |
     |cmpxchg +-H--+                                                       |
  20 +Emaster +-N--+                                                      ++
     ||                                                                    |
     |++                                                                   |
     ||                                                                    |
  15 +++                                                                  ++
     |N|                                                                   |
     |+|                                                                   |
  10 ++|                                                                  ++
     |+|+                                                                  |
     | |    -+E+------        +++  ---+E+------+E+------+E+-----+E+------+E|
     |+E+E+- +++     +E+------+E+--                                        |
   5 ++|+                                                                 ++
     |+N+H+---                                 +++                         |
     ++++N+--+H++----+++   +  +++  --++H+------+H+------+H++----+H+---+--- |
   0 ++---------+-----H----+---H-----+----------+----------+----------+---H+
     0          10         20        30         40         50         60
                                Number of threads

                atomic_add-bench: 5000000 ops/thread, [0,2] range

  25 ++---------+----------+---------+----------+----------+----------+---++
     ++atomic +-E--+       +         +          +          +          +    |
     |cmpxchg +-H--+                                                       |
  20 ++master +-N--+                                                      ++
     |E|                                                                   |
     |++                                                                   |
     ||E                                                                   |
  15 ++|                                                                  ++
     |N||                                                                  |
     |+||                                   ---+E+------+E+-----+E+------+E|
  10 ++| |        ---+E+------+E+-----+E+---                    +++      +++
     ||H+E+--+E+--                                                         |
     |+++++                                                                |
     | ||                                                                  |
   5 ++|+H+--                                  +++                        ++
     |+N+    -                              ---+H+------+H+------          |
     +  +N+--+H++----+H+---+--+H+----++H+---    +          +    +H+---+--+H|
   0 ++---------+----------+---------+----------+----------+----------+---++
     0          10         20        30         40         50         60
                                Number of threads

                atomic_add-bench: 5000000 ops/thread, [0,8] range

  40 ++---------+----------+---------+----------+----------+----------+---++
     ++atomic +-E--+       +         +          +          +          +    |
  35 +cmpxchg +-H--+                                                      ++
     | master +-N--+               ---+E+------+E+------+E+-----+E+------+E|
  30 ++|                   ---+E+--   +++                                 ++
     | |            -+E+---                                                |
  25 ++E        ---- +++                                                  ++
     |+++++ -+E+                                                           |
  20 +E+ E-- +++                                                          ++
     |H|+++                                                                |
     |+|                                       +H+-------                  |
  15 ++H+                                   ---+++      +H+------         ++
     |N++H+--                         +++---                    +H+------++|
  10 ++ +++  -       +++           ---+H+                       +++      +H+
     | |     +H+-----+H+------+H+--                                        |
   5 ++|                      +++                                         ++
     ++N+N+--+N++          +         +          +          +          +    |
   0 ++---------+----------+---------+----------+----------+----------+---++
     0          10         20        30         40         50         60
                                Number of threads

               atomic_add-bench: 5000000 ops/thread, [0,128] range

  160 ++---------+---------+----------+---------+----------+----------+---++
      + atomic +-E--+      +          +         +          +          +    |
  140 +cmpxchg +-H--+                          +++      +++               ++
      | master +-N--+                           E--------E------+E+------++|
  120 ++                                      --|        |      +++       E+
      |                                     -- +++      +++              ++|
  100 ++                                   -                              ++
      |                                +++-                     +++      ++|
   80 ++                              -+E+    -+H+------+H+------H--------++
      |                           ----    ----                  +++       H|
      |            ---+E+-----+E+-  ---+H+                               ++|
   60 ++     +E+---   +++  ---+H+---                                      ++
      |    --+++   ---+H+--                                                |
   40 ++ +E+-+H+---                                                       ++
      |  +H+                                                               |
   20 +EE+                                                                ++
      +N+        +         +          +         +          +          +    |
    0 ++N-N---N--+---------+----------+---------+----------+----------+---++
      0          10        20         30        40         50         60
                                Number of threads

              atomic_add-bench: 5000000 ops/thread, [0,1024] range

  350 ++---------+---------+----------+---------+----------+----------+---++
      + atomic +-E--+      +          +         +          +          +    |
  300 +cmpxchg +-H--+                                                    +++
      | master +-N--+                                           +++       ||
      |                                                 +++      |    ----E|
  250 ++                                                 |   ----E----    ++
      |                                              ----E---    |    ---+H|
  200 ++                                      -+E+---   +++  ---+H+---    ++
      |                                   ----         -+H+--              |
      |                                +E+     +++ ---- +++                |
  150 ++                            ---+++  ---+H+-                       ++
      |                          ---  -+H+--                               |
  100 ++                   ---+E+ ---- +++                                ++
      |      +++   ---+E+-----+H+-                                         |
      |     -+E+------+H+--                                                |
   50 ++ +E+                                                              ++
      +EE+       +         +          +         +          +          +    |
    0 ++N-N---N--+---------+----------+---------+----------+----------+---++
      0          10        20         30        40         50         60
                                Number of threads

  hi-res: http://imgur.com/a/fMRmq

For master I stopped measuring master after 8 threads, because there is little
point in measuring the well-known performance collapse of a contended lock.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1467054136-10430-21-git-send-email-cota@braap.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
2016-10-26 08:29:01 -07:00
audio trace-events: fix first line comment in trace-events 2016-08-12 10:36:01 +01:00
backends char: remove explicit_be_open from CharDriverState 2016-10-24 15:46:11 +02:00
block qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
bsd-user Put the copyright information on a separate line 2016-10-24 11:30:55 +02:00
contrib Clean up ill-advised or unusual header guards 2016-07-12 16:20:46 +02:00
crypto crypto: fix initialization of gcrypt threading 2016-10-20 12:19:35 +01:00
default-configs linux-user: disable unicore32 linux-user build 2016-10-21 15:20:14 +03:00
disas disas/arm.c: Remove unused macro definitions 2016-09-22 18:13:09 +01:00
docs qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
dtc@65cc4d2748 dtc: Update dtc / libfdt submodule to version 1.4.0 2015-06-03 23:56:49 +02:00
fpu fpu: add mechanism to check for invalid long double formats 2016-09-15 12:43:18 +01:00
fsdev 9pfs: fsdev: drop useless extern annotation for functions 2016-10-17 14:13:58 +02:00
gdb-xml target-ppc: gdbstub: Add VSX support 2016-01-30 23:37:38 +11:00
hw x86 and CPU queue, 2016-10-24 2016-10-25 10:25:27 +01:00
include tcg: Add atomic128 helpers 2016-10-26 08:29:01 -07:00
io trace: move util/buffer.c trace points into correct file 2016-09-28 19:17:54 +01:00
libdecnumber libdecnumber: Clean up includes 2016-02-16 14:29:27 +00:00
linux-headers linux-headers: update 2016-10-13 12:58:06 +11:00
linux-user linux-user: enable parallel code generation on clone 2016-10-26 08:29:00 -07:00
migration migration/savevm.c: migrate non-default page size 2016-10-24 16:26:50 +01:00
nbd nbd-server: Use a separate BlockBackend 2016-09-05 19:06:47 +02:00
net char: remove explicit_fe_open, use a set_handlers argument 2016-10-24 15:46:10 +02:00
pc-bios rules.mak: quiet-command: Split command name and args to print 2016-10-06 12:11:51 +01:00
pixman@87eea99e44 pixman: update internal copy to pixman-0.32.6 2014-09-15 08:14:19 +02:00
po rules.mak: quiet-command: Split command name and args to print 2016-10-06 12:11:51 +01:00
qapi qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
qga * Thread Sanitizer fixes (Alex) 2016-10-10 10:39:29 +01:00
qobject qdict: implement a qdict_crumple method for un-flattening a dict 2016-10-25 17:56:14 +02:00
qom qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
replay replay: allow replay stopping and restarting 2016-09-27 11:57:30 +02:00
roms Update OpenBIOS images to c5542f2 built from submodule. 2016-09-12 08:14:50 +01:00
scripts qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
slirp hw: replace most use of qemu_chr_fe_write with qemu_chr_fe_write_all 2016-09-13 19:09:42 +02:00
stubs tests: cleanup ptimer-test 2016-10-17 19:22:17 +01:00
target-alpha exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-arm x86 and CPU queue, 2016-10-24 2016-10-25 10:25:27 +01:00
target-cris exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-i386 target-i386: remove helper_lock() 2016-10-26 08:29:01 -07:00
target-lm32 exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-m68k exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-microblaze exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-mips exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-moxie exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-openrisc exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-ppc exec: call cpu_exec_exit() from a CPU unrealize common function 2016-10-24 17:29:16 -02:00
target-s390x qapi: rename QmpInputVisitor to QObjectInputVisitor 2016-10-25 16:25:54 +02:00
target-sh4 exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-sparc exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-tilegx exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-tricore exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-unicore32 exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
target-xtensa exec: move cpu_exec_init() calls to realize functions 2016-10-24 17:29:16 -02:00
tcg tcg: Emit barriers with parallel_cpus 2016-10-26 08:29:01 -07:00
tests int128: Use __int128 if available 2016-10-26 08:29:00 -07:00
trace trace: pass trace-events to tracetool as a positional param 2016-10-12 09:54:53 +02:00
ui char: remove explicit_be_open from CharDriverState 2016-10-24 15:46:11 +02:00
util qapi: rename *qmp-*-visitor* to *qobject-*-visitor* 2016-10-25 16:25:48 +02:00
.dir-locals.el Add .dir-locals.el file to configure emacs coding style 2015-10-08 19:46:01 +03:00
.exrc qemu: add .exrc 2012-09-07 09:02:44 +03:00
.gitignore trivial patches for 2016-10-08 2016-10-10 13:01:43 +01:00
.gitmodules PPC: Add u-boot firmware for e500 2014-06-16 13:24:35 +02:00
.mailmap Update mailmap 2013-09-05 09:40:31 -05:00
.travis.yml .travis.yml: add gcc sanitizer build 2016-10-04 10:00:26 +02:00
accel.c accel: make configure_accelerator return void 2016-05-18 15:04:27 +03:00
aio-posix.c aio-posix: avoid unnecessary aio_epoll_enabled() calls 2016-09-28 11:21:46 +01:00
aio-win32.c aio-posix: remove useless parameter 2016-07-18 15:10:52 +01:00
arch_init.c util: Add UUID API 2016-09-23 11:42:52 +08:00
async.c async: add aio_bh_schedule_oneshot 2016-10-07 13:34:07 +02:00
atomic_template.h tcg: Add atomic128 helpers 2016-10-26 08:29:01 -07:00
balloon.c all: Clean up includes 2016-02-04 17:41:30 +00:00
block.c block: Add qdev ID to DEVICE_TRAY_MOVED 2016-10-07 13:34:22 +02:00
blockdev-nbd.c nbd-server: Allow node name for nbd-server-add 2016-09-05 19:06:47 +02:00
blockdev.c qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
blockjob.c block: use aio_bh_schedule_oneshot 2016-10-07 13:34:07 +02:00
bootdevice.c error: Remove NULL checks on error_propagate() calls 2016-06-20 16:38:13 +02:00
bt-host.c all: Clean up includes 2016-02-04 17:41:30 +00:00
bt-vhci.c all: Clean up includes 2016-02-04 17:41:30 +00:00
Changelog Use qemu-project.org domain name 2013-10-11 09:34:56 -07:00
CODING_STYLE CODING_STYLE: Fix a typo ("have" vs. "has") 2016-10-08 11:25:29 +03:00
configure tcg: Add CONFIG_ATOMIC64 2016-10-26 08:29:01 -07:00
COPYING
COPYING.LIB Update FSF address in GPL/LGPL boilerplate 2009-01-04 22:05:52 +00:00
cpu-exec-common.c tcg: Add EXCP_ATOMIC 2016-10-26 08:29:00 -07:00
cpu-exec.c tcg: Add EXCP_ATOMIC 2016-10-26 08:29:00 -07:00
cpus-common.c cpus-common: lock-free fast path for cpu_exec_start/end 2016-09-27 11:57:30 +02:00
cpus.c tcg: Add EXCP_ATOMIC 2016-10-26 08:29:00 -07:00
cputlb.c tcg: Add CONFIG_ATOMIC64 2016-10-26 08:29:01 -07:00
device_tree.c qemu-common: stop including qemu/bswap.h from qemu-common.h 2016-05-19 16:42:28 +02:00
device-hotplug.c blockdev: Split monitor reference from BB creation 2016-03-17 15:47:56 +01:00
disas.c Remove remainders of HPPA backend 2016-09-15 15:32:22 +03:00
dma-helpers.c dma-helpers: dma_blk_io() cancel support 2016-06-28 13:08:31 +01:00
dump.c error: Remove NULL checks on error_propagate() calls 2016-06-20 16:38:13 +02:00
exec.c exec: Avoid direct references to Int128 parts 2016-10-26 08:29:00 -07:00
gdbstub.c char: remove explicit_fe_open, use a set_handlers argument 2016-10-24 15:46:10 +02:00
HACKING Disable warn about left shifts of negative values 2016-08-09 22:57:36 +02:00
hmp-commands-info.hx intc: make HMP 'info irq' and 'info pic' commands available on all targets 2016-10-04 10:00:25 +02:00
hmp-commands.hx monitor: remove mhandler.cmd_new 2016-09-19 17:32:22 +02:00
hmp.c char: remove init callback 2016-10-24 15:27:20 +02:00
hmp.h intc: make HMP 'info irq' and 'info pic' commands use InterruptStatsProvider interface 2016-10-04 10:00:25 +02:00
iohandler.c iohandler: Introduce iohandler_get_aio_context 2016-04-22 16:43:42 +02:00
ioport.c hw: remove pio_addr_t 2016-05-19 16:42:30 +02:00
iothread.c iothread: check iothread->ctx before aio_context_unref to avoid assertion 2016-09-28 11:21:46 +01:00
kvm-all.c kvm-all: don't use stale dbg_data->cpu 2016-10-23 16:10:59 +02:00
kvm-stub.c kvm-all: Pass requester ID to MSI routing functions 2016-10-04 13:28:09 +01:00
LICENSE vfio: move hw/misc/vfio.c to hw/vfio/pci.c Move vfio.h into include/hw/vfio 2014-12-19 15:24:06 -07:00
main-loop.c main-loop: check return value before using pointer 2016-07-12 18:31:27 +02:00
MAINTAINERS trivial patches for 2016-10-08 2016-10-10 13:01:43 +01:00
Makefile trace: get rid of generated-events.h/generated-events.c 2016-10-12 09:54:52 +02:00
Makefile.objs tcg: Add atomic helpers 2016-10-26 08:29:01 -07:00
Makefile.target tcg: Add atomic helpers 2016-10-26 08:29:01 -07:00
memory_mapping.c all: Remove unnecessary glib.h includes 2016-06-07 18:19:24 +03:00
memory.c memory: optimize memory_region_sync_dirty_bitmap 2016-10-24 15:27:19 +02:00
module-common.c all: Clean up includes 2016-02-04 17:41:30 +00:00
monitor.c qapi: rename *qmp-*-visitor* to *qobject-*-visitor* 2016-10-25 16:25:48 +02:00
numa.c numa: reduce code duplication by adding helper numa_get_node_for_cpu() 2016-10-10 01:16:57 +03:00
os-posix.c use g_path_get_dirname instead of dirname 2016-07-17 09:59:21 +02:00
os-win32.c all: Clean up includes 2016-02-04 17:41:30 +00:00
page_cache.c coccinelle: Remove unnecessary variables for function return value 2016-06-20 16:38:13 +02:00
qapi-schema.json trivial: Restore blank line in qapi-schema 2016-10-25 13:57:58 +02:00
qdev-monitor.c qdev-monitor: Add blk_by_qdev_id() 2016-09-23 13:36:10 +02:00
qdict-test-data.txt Introduce QDict test data file 2009-09-04 09:37:34 -05:00
qemu-bridge-helper.c all: Remove unnecessary glib.h includes 2016-06-07 18:19:24 +03:00
qemu-char.c char: remove explicit_be_open from CharDriverState 2016-10-24 15:46:11 +02:00
qemu-doc.texi qemu-doc: merge qemu-tech and qemu-doc 2016-10-07 10:05:54 +02:00
qemu-ga.texi docs: Style the command and its options in the synopsis 2016-01-26 15:58:11 +01:00
qemu-img-cmds.hx qemu-img: add skip option to dd 2016-09-20 22:10:57 +02:00
qemu-img.c qapi: rename QmpOutputVisitor to QObjectOutputVisitor 2016-10-25 16:25:54 +02:00
qemu-img.texi qemu-img: add skip option to dd 2016-09-20 22:10:57 +02:00
qemu-io-cmds.c block: switch blk_write_compressed() to byte-based interface 2016-09-05 19:06:47 +02:00
qemu-io.c trace: provide mechanism for registering trace events 2016-10-12 09:52:50 +02:00
qemu-nbd.c qemu-nbd: Add --fork option 2016-10-24 17:54:03 +02:00
qemu-nbd.texi qemu-nbd: Add --fork option 2016-10-24 17:54:03 +02:00
qemu-option-trace.texi doc: move text describing --trace to specific .texi file 2016-06-28 21:14:12 +01:00
qemu-options-wrapper.h vl.c: In qemu -h output, only print options for the arch we are running as 2011-12-19 10:27:33 -06:00
qemu-options.h Clean up ill-advised or unusual header guards 2016-07-12 16:20:46 +02:00
qemu-options.hx qemu-options.hx: fix -chardev ringbuf typos 2016-10-08 09:02:19 +03:00
qemu-seccomp.c seccomp: adding getrusage to the whitelist 2016-09-21 11:26:02 +02:00
qemu-tech.texi qemu-doc: merge qemu-tech and qemu-doc 2016-10-07 10:05:54 +02:00
qemu-timer.c timer: set vm_clock disabled default 2016-08-09 22:57:36 +02:00
qemu.nsi qemu-doc: merge qemu-tech and qemu-doc 2016-10-07 10:05:54 +02:00
qemu.sasl sasl: Avoid 'Could not find keytab file' in syslog 2014-03-15 13:54:18 +04:00
qmp.c qapi: rename QmpInputVisitor to QObjectInputVisitor 2016-10-25 16:25:54 +02:00
qtest.c char: remove explicit_fe_open, use a set_handlers argument 2016-10-24 15:46:10 +02:00
README qemu-doc: drop installation and compilation notes 2016-10-07 10:05:15 +02:00
replication.c replication: Introduce new APIs to do replication operation 2016-09-13 11:00:56 +01:00
replication.h replication: Introduce new APIs to do replication operation 2016-09-13 11:00:56 +01:00
rules.mak build-sys: fix find-in-path 2016-10-08 11:25:29 +03:00
softmmu_template.h cputlb: Tidy some macros 2016-10-26 08:29:00 -07:00
spice-qemu-char.c char: remove explicit_be_open from CharDriverState 2016-10-24 15:46:11 +02:00
tcg-runtime.c tcg: Add CONFIG_ATOMIC64 2016-10-26 08:29:01 -07:00
tci.c tcg/tci: Add support for fence 2016-09-16 08:12:12 -07:00
thread-pool.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
thunk.c thunk: Rename args and fields in host-target bitmask conversion code 2016-06-07 18:19:24 +03:00
tpm.c qapi: Don't special-case simple union wrappers 2016-03-18 10:29:26 +01:00
trace-events trace: Add missing execution mode of guest events 2016-10-12 09:54:53 +02:00
translate-all.c tcg: Add EXCP_ATOMIC 2016-10-26 08:29:00 -07:00
translate-all.h trace: Add per-vCPU tracing states for events with the 'vcpu' property 2016-07-18 18:23:12 +01:00
translate-common.c include: move CPU-related definitions out of qemu-common.h 2016-05-19 13:08:04 +02:00
user-exec.c tcg: Merge GETPC and GETRA 2016-09-16 08:12:11 -07:00
VERSION Open 2.8 development tree 2016-09-05 11:38:54 +01:00
version.rc Use qemu-project.org domain name 2013-10-11 09:34:56 -07:00
vl.c cpu: Support a target CPU having a variable page size 2016-10-24 16:26:49 +01:00
xen-common-stub.c xen: Clean up includes 2016-01-29 15:07:23 +00:00
xen-common.c xen: drop XenXC and associated interface wrappers 2016-02-10 12:01:24 +00:00
xen-hvm-stub.c fix MSI injection on Xen 2016-02-06 20:44:10 +02:00
xen-hvm.c xen: handle inbound migration of VMs without ioreq server pages 2016-08-12 16:38:30 -07:00
xen-mapcache.c os-posix: include sys/mman.h 2016-06-16 18:39:03 +02:00

README 

         QEMU README
         ===========

QEMU is a generic and open source machine & userspace emulator and
virtualizer.

QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).

QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.

QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.

QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.


Building
========

QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:

  mkdir build
  cd build
  ../configure
  make

Additional information can also be found online via the QEMU website:

  http://qemu-project.org/Hosts/Linux
  http://qemu-project.org/Hosts/W32


Submitting patches
==================

The QEMU source code is maintained under the GIT version control system.

   git clone git://git.qemu-project.org/qemu.git

When submitting patches, the preferred approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the HACKING and CODING_STYLE files.

Additional information on submitting patches can be found online via
the QEMU website

  http://qemu-project.org/Contribute/SubmitAPatch
  http://qemu-project.org/Contribute/TrivialPatches


Bug reporting
=============

The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:

  https://bugs.launchpad.net/qemu/

If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.

For additional information on bug reporting consult:

  http://qemu-project.org/Contribute/ReportABug


Contact
=======

The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC

 - qemu-devel@nongnu.org
   http://lists.nongnu.org/mailman/listinfo/qemu-devel
 - #qemu on irc.oftc.net

Information on additional methods of contacting the community can be
found online via the QEMU website:

  http://qemu-project.org/Contribute/StartHere

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