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charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" bugzilla-daemon@bugzilla.kernel.org's on February 26, 2020 8:28 pm: > https://bugzilla.kernel.org/show_bug.cgi?id=3D206669 >=20 > --- Comment #4 from John Paul Adrian Glaubitz (glaubitz@physik.fu-berlin.= de) --- > (In reply to npiggin from comment #3) >> Do you have tracing / ftrace enabled in the host kernel for any >> reason? Turning that off might let the oops message get printed. >=20 > Seems that this is the case in the Debian kernel, yes: >=20 > root@watson:~# grep -i ftrace /boot/config-5.4.0-0.bpo.3-powerpc64le=20 > CONFIG_KPROBES_ON_FTRACE=3Dy > CONFIG_HAVE_KPROBES_ON_FTRACE=3Dy > CONFIG_HAVE_DYNAMIC_FTRACE=3Dy > CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS=3Dy > CONFIG_HAVE_FTRACE_MCOUNT_RECORD=3Dy > CONFIG_FTRACE=3Dy > CONFIG_FTRACE_SYSCALLS=3Dy > CONFIG_DYNAMIC_FTRACE=3Dy > CONFIG_DYNAMIC_FTRACE_WITH_REGS=3Dy > CONFIG_FTRACE_MCOUNT_RECORD=3Dy > # CONFIG_FTRACE_STARTUP_TEST is not set > root@watson:~# >=20 > Do you have the kernel command option at hand which disables ftrace on th= e > command line? Is it just ftrace=3Doff? Hmm, not sure, Documentation/admin-guide/kernel-parameters.txt seems to say that wouldn't work. I thought it might only be going down that path if you have already done some tracing. Perhaps ensure /sys/kernel/debug/tracing/tracing_on is set to 0, and then `echo 1 > /sys/kernel/debug/tracing/free_buffer` before you start the test. >> > FWIW, the kernel image comes from this Debian package: >> >=20 >> >> >> >> >> >> >> http://snapshot.debian.org/archive/debian/20200211T210433Z/pool/main/l/l= inux/linux-image-5.4.0-0.bpo.3-powerpc64le_5.4.13-1%7Ebpo10%2B1_ppc64el.deb >>=20 >> Okay. Any chance you could test an upstream kernel?=20 >=20 > Sure, absolutely. Any preference on the version number? Current head if you're feeling lucky, but v5.5 if not. But you can give the ftrace test a try with the debian kernel first if you've got it ready to go. >> Don't bother testing that after the above -- panic_on_oops happens >> after oops_begin(), so it won't help unfortunately. >=20 > Okay. >=20 >> Attmepting to get into xmon might though, if you boot with xmon=3Don. >> Try that if tracing wasn't enabled, or disabling it doesn't help. >=20 > Okay. I will try to disable ftrace first, then retrigger the crash. Cool Thanks, Nick =