[Qemu-devel] 'tcg fatal error' with qemu v2.6.0-rc3 (bisected)

[Qemu-devel] 'tcg fatal error' with qemu v2.6.0-rc3 (bisected)

[Guenter Roeck]

Hi,

when running qemu version 2.6.0-rc3, I get the following error message.

/opt/buildbot/qemu/qemu/tcg/tcg.c:1769: tcg fatal error

qemu command line is as follows.

qemu-system-ppc64 -M mpc8544ds \
	-cpu e5500 \
	-m 1024 -kernel arch/powerpc/boot/uImage -initrd busybox-ppc.cpio \
	-nographic -vga none -monitor null -no-reboot \
	--append "rdinit=/sbin/init console=tty console=ttyS0" \
	-machine "dt_compatible=fsl,,P5020DS"

Files are from my test suite at https://github.com/groeck/linux-build-test.

Bisect points to commit 40ae5c62ebaaf7d9d3b93b88c2d32bf6342f7889 ("tcg:
Introduce temp_load"). Bisect log is attached.

Guenter

---
# 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
# bad: [c9f19dff101e2c2cf3fa3967eceec2833e845e40] Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging
git bisect bad c9f19dff101e2c2cf3fa3967eceec2833e845e40
# bad: [977a82ab56daac83623d730174f47d5a7edd73c9] configure: sanity check the glib library that pkg-config finds
git bisect bad 977a82ab56daac83623d730174f47d5a7edd73c9
# good: [a86156401559cb4401cf9ecc704faeab6fc8bb19] qmp: Fix reference-counting of qnull on empty output visit
git bisect good a86156401559cb4401cf9ecc704faeab6fc8bb19
# good: [12b9b11a2743002232098afb41810f1c0cb211a0] tcg: Change temp_sync argument to TCGTemp
git bisect good 12b9b11a2743002232098afb41810f1c0cb211a0
# bad: [ac1be2ae6b2995b99430c48329eb971b0281acf1] Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2016-02-09' into staging
git bisect bad ac1be2ae6b2995b99430c48329eb971b0281acf1
# good: [423aeaf219890e8a7311dbeef1a925020027c2ea] qapi: Add missing JSON files in build dependencies
git bisect good 423aeaf219890e8a7311dbeef1a925020027c2ea
# bad: [40ae5c62ebaaf7d9d3b93b88c2d32bf6342f7889] tcg: Introduce temp_load
git bisect bad 40ae5c62ebaaf7d9d3b93b88c2d32bf6342f7889
# good: [b13eb728d33deaa53efc0dcef557da998e6ec40e] tcg: Change temp_save argument to TCGTemp
git bisect good b13eb728d33deaa53efc0dcef557da998e6ec40e
# first bad commit: [40ae5c62ebaaf7d9d3b93b88c2d32bf6342f7889] tcg: Introduce temp_load

Re: [Qemu-devel] 'tcg fatal error' with qemu v2.6.0-rc3 (bisected)

[Aurelien Jarno]

On 2016-04-26 20:12, Guenter Roeck wrote:
> Hi,
> 
> when running qemu version 2.6.0-rc3, I get the following error message.
> 
> /opt/buildbot/qemu/qemu/tcg/tcg.c:1769: tcg fatal error
> 
> qemu command line is as follows.
> 
> qemu-system-ppc64 -M mpc8544ds \
> 	-cpu e5500 \
> 	-m 1024 -kernel arch/powerpc/boot/uImage -initrd busybox-ppc.cpio \
> 	-nographic -vga none -monitor null -no-reboot \
> 	--append "rdinit=/sbin/init console=tty console=ttyS0" \
> 	-machine "dt_compatible=fsl,,P5020DS"
> 
> Files are from my test suite at https://github.com/groeck/linux-build-test.

I have try to reproduce the issue with a kernel build with my toolchain
and your defconfig, but it worked for me. Could you please share the
binaries so that it is easier to reproduce the issue?

> Bisect points to commit 40ae5c62ebaaf7d9d3b93b88c2d32bf6342f7889 ("tcg:
> Introduce temp_load"). Bisect log is attached.

I look at this patch again quickly, and I don't think the bug is
actually introduced by this commit, it is just that it does more strict
tests on the value. I guess it was working before by chance by loading
a random value into the register. That said to look deeper into it, it
would be better to be able to reproduce the issue.

Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net

Re: [Qemu-devel] 'tcg fatal error' with qemu v2.6.0-rc3 (bisected)

[Guenter Roeck]

On Wed, Apr 27, 2016 at 08:57:24AM +0200, Aurelien Jarno wrote:
> On 2016-04-26 20:12, Guenter Roeck wrote:
> > Hi,
> > 
> > when running qemu version 2.6.0-rc3, I get the following error message.
> > 
> > /opt/buildbot/qemu/qemu/tcg/tcg.c:1769: tcg fatal error
> > 
> > qemu command line is as follows.
> > 
> > qemu-system-ppc64 -M mpc8544ds \
> > 	-cpu e5500 \
> > 	-m 1024 -kernel arch/powerpc/boot/uImage -initrd busybox-ppc.cpio \
> > 	-nographic -vga none -monitor null -no-reboot \
> > 	--append "rdinit=/sbin/init console=tty console=ttyS0" \
> > 	-machine "dt_compatible=fsl,,P5020DS"
> > 
> > Files are from my test suite at https://github.com/groeck/linux-build-test.
> 
> I have try to reproduce the issue with a kernel build with my toolchain
> and your defconfig, but it worked for me. Could you please share the
> binaries so that it is easier to reproduce the issue?
> 
I forgot to mention - it happens during reboot.

Assuming you are using my root file system, try adding "doreboot" to the command
line.

Thanks,
Guenter

> > Bisect points to commit 40ae5c62ebaaf7d9d3b93b88c2d32bf6342f7889 ("tcg:
> > Introduce temp_load"). Bisect log is attached.
> 
> I look at this patch again quickly, and I don't think the bug is
> actually introduced by this commit, it is just that it does more strict
> tests on the value. I guess it was working before by chance by loading
> a random value into the register. That said to look deeper into it, it
> would be better to be able to reproduce the issue.
> 
> Aurelien
> 
> -- 
> Aurelien Jarno                          GPG: 4096R/1DDD8C9B
> aurelien@aurel32.net                 http://www.aurel32.net