Re: [Qemu-devel] [PATCH v3 00/11] simplify usage of tracepoints, and connect them to logging

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Thu, Oct 29, 2015 at 11:44:06PM +0300, Denis V. Lunev wrote:
> This series does three things:
> 
> 1) add a "-trace [enable=]foo" option to enable one or more trace
> events, and a "-trace help" option to show the list of tracepoints
> (patches 4-5)
> 
> 2) change the stderr tracing backend so that it prints to the
> -D log file, and enable it by default.  "-trace file=..." is
> now a synonym of -D if the log backend is enabled (patches 7-8)
> 
> 3) add a "-d trace:foo" option that is a synonym for "-trace foo";
> this makes the new functionality more discoverable to people used
> to "-d", makes it available for user-mode emulation (which does
> not have -trace), and is somewhat nice if you want to enable both
> tracepoints and some other "-d" flag (patch 9).  When globbing
> it is also less susceptible to unwanted shell expansion.
> 
> For example, you can trace block device I/O and save the result
> to a file just by adding "-trace bdrv_aio_*,file=trace.txt", or
> correlate it to guest PCs with "-d exec,nochain,trace:bdrv_aio_*".
> 
> Opinions?  I would like to have this in 2.5 if there is agreement.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> 
> Changes from v2:
> - compilation fix was extended to patch 2 and 3
> - replaced Reviewed-by with Acked-by by request from Christian
> 
> Changes from v1:
> - small cleanup to vl.c is added as patch (4)
> - compilation is fixed in patch (2)
> - moved qemu-log.c to util/log.c to fix linking of qemu-io/qemu-nbd
> 
> Denis V. Lunev (2):
>   trace: no need to call trace_backend_init in different branches now
>   log: move qemu-log.c into util/ directory
> 
> Paolo Bonzini (9):
>   trace: fix documentation
>   trace: split trace_init_events out of trace_init_backends
>   trace: split trace_init_file out of trace_init_backends
>   trace: add "-trace enable=..."
>   trace: add "-trace help"
>   log: do not unnecessarily include qom/cpu.h
>   trace: convert stderr backend to log
>   trace: switch default backend to "log"
>   log: add "-d trace:PATTERN"
> 
>  Makefile.objs                                   |  1 -
>  bsd-user/main.c                                 |  1 +
>  configure                                       |  6 +-
>  cpu-exec.c                                      |  1 +
>  exec.c                                          |  1 +
>  hw/acpi/cpu_hotplug.c                           |  1 +
>  hw/timer/a9gtimer.c                             |  1 +
>  include/exec/log.h                              | 60 ++++++++++++++++
>  include/qemu/log.h                              | 60 +---------------
>  linux-user/main.c                               |  1 +
>  qemu-io.c                                       |  2 +-
>  qemu-options.hx                                 | 22 ++++--
>  qom/cpu.c                                       |  1 +
>  scripts/tracetool/backend/{stderr.py => log.py} |  9 +--
>  target-alpha/translate.c                        |  1 +
>  target-arm/translate.c                          |  1 +
>  target-cris/translate.c                         |  1 +
>  target-i386/seg_helper.c                        |  1 +
>  target-i386/smm_helper.c                        |  1 +
>  target-i386/translate.c                         |  1 +
>  target-lm32/helper.c                            |  1 +
>  target-lm32/translate.c                         |  1 +
>  target-m68k/translate.c                         |  1 +
>  target-microblaze/helper.c                      |  1 +
>  target-microblaze/translate.c                   |  1 +
>  target-mips/helper.c                            |  1 +
>  target-mips/translate.c                         |  1 +
>  target-moxie/translate.c                        |  1 +
>  target-openrisc/translate.c                     |  1 +
>  target-ppc/mmu-hash32.c                         |  1 +
>  target-ppc/mmu-hash64.c                         |  1 +
>  target-ppc/mmu_helper.c                         |  1 +
>  target-ppc/translate.c                          |  1 +
>  target-s390x/translate.c                        |  1 +
>  target-sh4/helper.c                             |  1 +
>  target-sh4/translate.c                          |  1 +
>  target-sparc/int32_helper.c                     |  1 +
>  target-sparc/int64_helper.c                     |  1 +
>  target-sparc/translate.c                        |  1 +
>  target-tilegx/translate.c                       |  1 +
>  target-tricore/translate.c                      |  1 +
>  target-unicore32/translate.c                    |  1 +
>  target-xtensa/translate.c                       |  1 +
>  tcg/tcg.c                                       |  1 +
>  trace/control.c                                 | 95 ++++++++++++++++++-------
>  trace/control.h                                 | 42 ++++++++++-
>  trace/simple.c                                  |  6 +-
>  trace/simple.h                                  |  4 +-
>  translate-all.c                                 |  1 +
>  util/Makefile.objs                              |  1 +
>  qemu-log.c => util/log.c                        | 19 ++++-
>  vl.c                                            | 38 +++++-----
>  52 files changed, 274 insertions(+), 129 deletions(-)
>  create mode 100644 include/exec/log.h
>  rename scripts/tracetool/backend/{stderr.py => log.py} (78%)
>  rename qemu-log.c => util/log.c (90%)

Hi Denis,
I have pasted the issues that Peter Maydell hit during QEMU 2.5 below.
Please rebase this series onto
https://github.com/stefanha/qemu/commits/tracing-pull-request
(cef517ca4bf890ef5405aac1b95f75dcda043d6a)

I'll rerun the Windows build on the next revision to make sure the
warnings have been fixed.

Thanks,
Stefan
---

1.
Fails to build on all platforms :-(

/home/petmay01/linaro/qemu-for-merges/target-arm/translate-a64.c: In
function ‘gen_intermediate_code_a64’:
/home/petmay01/linaro/qemu-for-merges/target-arm/translate-a64.c:11229:9:
error: implicit declaration of function ‘lookup_symbol’
[-Werror=implicit-function-declaration]
         qemu_log("IN: %s\n", lookup_symbol(pc_start));
         ^
/home/petmay01/linaro/qemu-for-merges/target-arm/translate-a64.c:11229:9:
error: nested extern declaration of ‘lookup_symbol’
[-Werror=nested-externs]
/home/petmay01/linaro/qemu-for-merges/target-arm/translate-a64.c:11229:9:
error: format ‘%s’ expects argument of type ‘char *’, but argument 2
has type ‘int’ [-Werror=format=]
/home/petmay01/linaro/qemu-for-merges/target-arm/translate-a64.c:11230:9:
error: implicit declaration of function ‘log_target_disas’
[-Werror=implicit-function-declaration]
         log_target_disas(cs, pc_start, dc->pc - pc_start,
         ^
/home/petmay01/linaro/qemu-for-merges/target-arm/translate-a64.c:11230:9:
error: nested extern declaration of ‘log_target_disas’
[-Werror=nested-externs]
cc1: all warnings being treated as errors

2.
w32 fails to build with the same 'ssize_t vs signed size_t for %zd'
thing that hit somebody else's changes earlier this week:

In file included from /home/petmay01/linaro/qemu-for-merges/include/trace.h:4,
                 from
/home/petmay01/linaro/qemu-for-merges/util/oslib-win32.c:38:
./trace/generated-tracers.h: In function ‘trace_virtio_console_flush_buf’:
./trace/generated-tracers.h:240: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 8 has type ‘ssize_t’
  CC    util/bitops.o
./trace/generated-tracers.h: In function ‘trace_usb_ohci_iso_td_so’:
./trace/generated-tracers.h:2784: warning: format ‘%zu’ expects type
‘size_t’, but argument 11 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_usb_ohci_iso_td_data_overrun’:
./trace/generated-tracers.h:2796: warning: format ‘%zu’ expects type
‘size_t’, but argument 7 has type ‘ssize_t’
  CC    util/hbitmap.o
  CC    util/fifo8.o
./trace/generated-tracers.h: In function ‘trace_spice_vmc_write’:
./trace/generated-tracers.h:6492: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 6 has type ‘ssize_t’
  CC    util/acl.o
  CC    util/error.o
./trace/generated-tracers.h: In function ‘trace_v9fs_read_return’:
./trace/generated-tracers.h:10344: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 9 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_v9fs_readdir_return’:
./trace/generated-tracers.h:10368: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 9 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_v9fs_write_return’:
./trace/generated-tracers.h:10392: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 9 has type ‘ssize_t’
  CC    util/qemu-error.o
  CC    util/id.o
  CC    util/iov.o
cc1: warnings being treated as errors
In file included from /home/petmay01/linaro/qemu-for-merges/include/trace.h:4,
                 from /home/petmay01/linaro/qemu-for-merges/util/hbitmap.c:18:
./trace/generated-tracers.h: In function ‘trace_virtio_console_flush_buf’:
./trace/generated-tracers.h:240: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 8 has type ‘ssize_t’
  CC    util/qemu-config.o
./trace/generated-tracers.h: In function ‘trace_usb_ohci_iso_td_so’:
./trace/generated-tracers.h:2784: warning: format ‘%zu’ expects type
‘size_t’, but argument 11 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_usb_ohci_iso_td_data_overrun’:
./trace/generated-tracers.h:2796: warning: format ‘%zu’ expects type
‘size_t’, but argument 7 has type ‘ssize_t’
make: *** [util/oslib-win32.o] Error 1
make: *** Waiting for unfinished jobs....
./trace/generated-tracers.h: In function ‘trace_spice_vmc_write’:
./trace/generated-tracers.h:6492: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 6 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_v9fs_read_return’:
./trace/generated-tracers.h:10344: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 9 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_v9fs_readdir_return’:
./trace/generated-tracers.h:10368: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 9 has type ‘ssize_t’
./trace/generated-tracers.h: In function ‘trace_v9fs_write_return’:
./trace/generated-tracers.h:10392: warning: format ‘%zd’ expects type
‘signed size_t’, but argument 9 has type ‘ssize_t’
make: *** [util/hbitmap.o] Error 1
make: Leaving directory `/home/petmay01/linaro/qemu-for-merges/build/w32'

3.
I also now get a handful of extra warnings in the 'make check' output:

  /aarch64/qom/xilinx-zynq-a9:                                         OK
  /aarch64/qom/xlnx-ep108:
WARNING: RAM size 8000000 is small for EP108OK
  /aarch64/qom/vexpress-a9:                                            OK

(note the missing newline...)

TEST: tests/qom-test... (pid=19738)
  /microblaze/qom/none:                                                OK
  /microblaze/qom/petalogix-s3adsp1800:
Invalid MicroBlaze version number: (null)
OK
  /microblaze/qom/petalogix-ml605:
Invalid MicroBlaze version number: (null)
OK

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