[Qemu-devel] [Bug 1715700] Re: Windows 7 guest won't boot on qemu 2.10 (works on 2.9)

[Aleksei Kovura]

Ok, so I cloned from github and am bisecting like this (it's been a while, 
correct me if I'm wrong):
$ git bisect start
$ git bisect bad 1ab5eb4efb91a3d4569b0df6e824cc08ab4bd8ec # 2.10.0 stable commit
$ git bisect good 359c41abe32638adad503e386969fa428cecff52 # 2.9.0 stable commit
Bisecting: 1426 revisions left to test after this (roughly 11 steps)
[269c20b2bbd2aa8531e0cdc741fb166f290d7a2b] tests/qdict: check more 
get_try_int() cases
$ mkdir -p bin/269c20b2bbd2aa8531e0cdc741fb166f290d7a2b
$ cd bin/269c20b2bbd2aa8531e0cdc741fb166f290d7a2b
$ ../../configure --target-list=x86_64-softmmu --python=/usr/bin/python2 
--enable-debug

Compilation fails with this (full log here
https://pastebin.com/aUYyE6Bb):

  CC      block/block-backend.o
/media/usb465gb_232gb_NTFS/compile/qemu/block/blkdebug.c: In function 
‘blkdebug_refresh_filename’:
/media/usb465gb_232gb_NTFS/compile/qemu/block/blkdebug.c:843:31: error: ‘%s’ 
directive output may be truncated writing up to 4095 bytes into a region of 
size 4086 [-Werror=format-truncation=]
                  "blkdebug:%s:%s", s->config_file ?: "",
                               ^~
/media/usb465gb_232gb_NTFS/compile/qemu/block/blkdebug.c:842:9: note: 
‘snprintf’ output 11 or more bytes (assuming 4106) into a destination of size 
4096
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  "blkdebug:%s:%s", s->config_file ?: "",
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  bs->file->bs->exact_filename);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/media/usb465gb_232gb_NTFS/compile/qemu/rules.mak:66: 
block/blkdebug.o] Error 1
make: *** Waiting for unfinished jobs....
/media/usb465gb_232gb_NTFS/compile/qemu/block/blkverify.c: In function 
‘blkverify_refresh_filename’:
/media/usb465gb_232gb_NTFS/compile/qemu/block/blkverify.c:305:29: error: ‘%s’ 
directive output may be truncated writing up to 4095 bytes into a region of 
size 4086 [-Werror=format-truncation=]
                  "blkverify:%s:%s",
                             ^~
/media/usb465gb_232gb_NTFS/compile/qemu/block/blkverify.c:304:9: note: 
‘snprintf’ output between 12 and 8202 bytes into a destination of size 4096
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  "blkverify:%s:%s",
                  ~~~~~~~~~~~~~~~~~~
                  bs->file->bs->exact_filename,
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  s->test_file->bs->exact_filename);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/media/usb465gb_232gb_NTFS/compile/qemu/rules.mak:66: 
block/blkverify.o] Error 1

Did I hit a commit with a broken build or something? What to do next?

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https://bugs.launchpad.net/bugs/1715700

Title:
  Windows 7 guest won't boot on qemu 2.10 (works on 2.9)

Status in QEMU:
  New

Bug description:
  Qemu version: 2.10 stable.
  Guest: Windows 7 SP1 x64, virtio drivers are already installed in the guest.
  Command line:
  qemu-system-x86_64 \
      -nodefaults \
      -nodefconfig \
      -machine type=q35,accel=kvm \
      -enable-kvm \
      -cpu host \
      -m 2048 \
      -vga virtio \
      -boot menu=on \
      -smbios file=/path/dmidecode_BIOS.bin \
      -acpitable file=/path/acpi_slic.bin \
      -bios /path/OVMF_CODE.fd \
      -net none \
      -drive if=virtio,media=disk,file=/media/win7.qcow2 \
      -device pcie-root-port \
      -device ich9-usb-ehci1 \
      -device ich9-usb-uhci1 \
      -device ich9-usb-uhci2 \
      -device ich9-usb-uhci3

  Windows hangs at boot with waving flag screen (flag doesn't freeze,
  keeps waving indefinitely). Same command line boots fine with Qemu
  2.9. I tried changing machine type to pc-q35-2.9 - same result.

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