[Qemu-devel] [PATCH v2 0/5] fix qxl screendump using monitor_suspend

[Alon Levy]

v2 changes:
 rearranged and split the last patch:
  the console change to add Monitor to vga_hw_screen_dump can be moved past the
  qxl change, making it easier to see the changes, and adding an intermediate
  point where ppm_save happens after the update, but the do_screen_dump returns
  before ppm_save.
 The title of the patchset is wrong, only hmp is fixed, but qmp is now broken
  in a different way: there is no file saved when it expects it. The solution to
  this can be a change to libvirt to use hmp command for screendump when a qxl
  device is used, until the QAPI async monitor commands change lands.

This patchset starts and ends with trace event additions that make it easier to 
see the change.

It applies on top of 
http://lists.gnu.org/archive/html/qemu-devel/2012-03/msg01784.html
due to trace-events.

The problem addressed by this patchset is that after recent fixes (81fb6f)
screendump with a qxl device in native mode saves a stale screen dump.

The solution is to use monitor_suspend and monitor_release in qxl's 
implementation.

This is done by:
 1. introducing an extra parameter to vga_hw_screen_dump & hw_vga_dump
  console: pass Monitor to vga_hw_screen_dump/hw_vga_dump
 2. using it in qxl via a bh.
  qxl-render: call ppm_save on bh

Additional patches add trace events to qxl and qxl_render, making it easy to 
see the difference:

events setup: (using stderr backend)

(qemu) trace-event ppm_save on
(qemu) trace-event qxl* on
(qemu) trace-event qxl_interface_get_command_enter off
(qemu) trace-event qxl_interface_release_resource off
(qemu) trace-event qxl_interface_get_command_ret off

before: ppm_save done before update:

    (qemu) screendump /tmp/a.ppm
    ppm_save /tmp/a.ppm surface=0x7fc0267b3ad0
    qxl_interface_update_area_complete surface=0 [152,160,464,480] #=1
    qxl_interface_update_area_complete_schedule_bh #dirty=1
    qxl_render_update_area_done 0x7fc02b603db0
    (qemu) qxl_blit stride=-2560 [152, 160, 464, 480]

after:

    (qemu) screendump /tmp/a.ppm
    qxl_interface_update_area_complete surface=0 [152,160,464,480] #=1
    qxl_interface_update_area_complete_schedule_bh #dirty=1
    qxl_render_update_area_done 0x7f407af72210
    qxl_render_ppm_save_bh 0x7f407f845b60 (primary 0x7f401bc00000)
    qxl_blit stride=-2560 [152, 160, 464, 480]
    ppm_save /tmp/a.ppm surface=0x7f4077204ad0
    (qemu)

Note: This doesn't address a possible libvirt problem that was mentioned in
length before, but since it has not been reproduced it will be fixed when it
is. Meanwhile other users like autotest will be fixed by this patch (by fix I
mean screendump will produce the correct output).


Alon Levy (5):
  qxl: switch qxl.c to trace-events
  qxl/qxl_render.c: add trace events
  qxl-render: call ppm_save on bh
  console: pass Monitor to vga_hw_screen_dump/hw_vga_dump
  qxl: screendump: use provided Monitor

 console.c          |    4 +-
 console.h          |    5 +-
 hw/blizzard.c      |    2 +-
 hw/g364fb.c        |    3 +-
 hw/omap_dss.c      |    4 +-
 hw/omap_lcdc.c     |    3 +-
 hw/qxl-render.c    |   95 +++++++++++++++++++++++++++------
 hw/qxl.c           |  150 ++++++++++++++++++++++++---------------------------
 hw/qxl.h           |    2 +-
 hw/sm501.c         |    4 +-
 hw/tcx.c           |   12 +++--
 hw/vga.c           |    6 ++-
 hw/vmware_vga.c    |    5 +-
 monitor.c          |    2 +-
 trace-events       |   55 +++++++++++++++++++
 ui/spice-display.h |    3 +
 16 files changed, 240 insertions(+), 115 deletions(-)

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1.7.9.1