[Qemu-devel] Hangs with qemu v2.6.0-rc3 (qemu-system-x86_64) (bisected)

[Guenter Roeck]

Hi,

In qemu version 2.6.0-rc3, qemu-system-x86_64 hangs for me for some CPU/machine
combinations. Some affected combinations are SandyBridge (q35), Haswell (q35),
Opteron_G4 (pc), IvyBridge (q35). Some working combinations are core2duo (pc),
Nehalem (q35), phenom (pc), Opteron_G1 (q35).

On the broken combinations, there is no console output other than TCG
warnings, such as

warning: TCG doesn't support requested feature: CPUID.01H:EDX.vme [bit 1]

Qemu command line is as follows.

qemu-system-x86_64 \
        -kernel arch/x86/boot/bzImage \
        -M q35 -cpu SandyBridge -usb -usbdevice wacom-tablet \
        -hda core-image-minimal-qemux86-64.ext3 -no-reboot -m 256 \
        --append "root=/dev/sda rw mem=256M vga=0 
uvesafb.mode_option=640x480-32 oprofile.timer=1 console=ttyS0 console= tty" \
        -nographic -monitor none

The problem seems to be kernel version independent; I have seen it with 3.2,
mainline, and -next kernels. The kernel configuration as well as the root
file system are available from
https://github.com/groeck/linux-build-test/tree/master/rootfs/x86_64

Bisect points to commit 19dc85dba23c0 ("target-i386: Add XSAVE extension").
Bisect log is attached.

Please let me know if there is anything I can do to help tracking down the
problem.

Thanks,
Guenter

---
Bisect log:

# bad: [f419a626c76bcb26697883af702862e8623056f9] usb/uhci: move pid check
# good: [a8c40fa2d667e585382080db36ac44e216b37a1c] Update version for v2.5.0 
release
git bisect start 'HEAD' 'v2.5.0'
# bad: [253785e3b96f48c52568c312cec0a5ec596c527f] scripts/feature_to_c.sh: 
Include qemu/osdep.h rather than config.h
git bisect bad 253785e3b96f48c52568c312cec0a5ec596c527f
# good: [f4109dba216f2df61a6098fdd7a6f2d2be4ac848] scripts/kvm/kvm_stat: Moved 
DebugfsProvider
git bisect good f4109dba216f2df61a6098fdd7a6f2d2be4ac848
# good: [8983b670f62ab5e5e8dd2690bf8304123651bfe5] block: qemu-iotests - add 
test for snapshot, commit, snapshot bug
git bisect good 8983b670f62ab5e5e8dd2690bf8304123651bfe5
# good: [d7bea75d35a44023efc9d481d3a1a2600677b2ef] qapi: Avoid use of misnamed 
DO_UPCAST()
git bisect good d7bea75d35a44023efc9d481d3a1a2600677b2ef
# good: [c9f19dff101e2c2cf3fa3967eceec2833e845e40] Merge remote-tracking branch 
'remotes/bonzini/tags/for-upstream' into staging
git bisect good c9f19dff101e2c2cf3fa3967eceec2833e845e40
# good: [fc1ec1acffd29d54c0c4266d30d38b2399d42f4f] Merge remote-tracking branch 
'remotes/mjt/tags/pull-trivial-patches-2016-02-11' into staging
git bisect good fc1ec1acffd29d54c0c4266d30d38b2399d42f4f
# bad: [62b58ba58bfebdb8a1c447beaa1285cc21249d15] target-i386: Implement BNDMOV
git bisect bad 62b58ba58bfebdb8a1c447beaa1285cc21249d15
# good: [1906b2af7c2345037d9b2fdf484b457b5acd09d1] target-i386: Rearrange 
processing of 0F 01
git bisect good 1906b2af7c2345037d9b2fdf484b457b5acd09d1
# bad: [f4f1110e4b34797ddfa87bb28f9518b9256778be] target-i386: Enable control 
registers for MPX
git bisect bad f4f1110e4b34797ddfa87bb28f9518b9256778be
# bad: [19dc85dba23c0db1ca932c62e453c37e00761628] target-i386: Add XSAVE 
extension
git bisect bad 19dc85dba23c0db1ca932c62e453c37e00761628
# good: [121f3157887f92268a3d6169e2d4601f9292020b] target-i386: Rearrange 
processing of 0F AE
git bisect good 121f3157887f92268a3d6169e2d4601f9292020b
# first bad commit: [19dc85dba23c0db1ca932c62e453c37e00761628] target-i386: Add 
XSAVE extension