From: Don Zickus <dzickus@redhat.com>
To: Chen Gong <gong.chen@linux.intel.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>,
"Luck, Tony" <tony.luck@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Matthew Garrett <mjg@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
"Chen, Gong" <gong.chen@intel.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"Brown, Len" <len.brown@intel.com>,
"'ying.huang@intel.com'" <'ying.huang@intel.com'>,
"'ak@linux.intel.com'" <'ak@linux.intel.com'>,
"'hughd@chromium.org'" <'hughd@chromium.org'>,
"'mingo@elte.hu'" <'mingo@elte.hu'>,
"jmorris@namei.org" <jmorris@namei.org>,
"a.p.zijlstra@chello.nl" <a.p.zijlstra@chello.nl>,
"namhyung@gmail.com" <namhyung@gmail.com>,
"dle-develop@lists.sourceforge.net"
<dle-develop@lists.sourceforge.net>,
Satoru Moriya <satoru.moriya@hds.com>
Subject: Re: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop()
Date: Wed, 11 Jan 2012 12:25:44 -0500 [thread overview]
Message-ID: <20120111172544.GS5650@redhat.com> (raw)
In-Reply-To: <4F0D3A0B.4090709@linux.intel.com>
On Wed, Jan 11, 2012 at 03:28:11PM +0800, Chen Gong wrote:
> 于 2012/1/11 4:29, Seiji Aguchi 写道:
> >
> >>I agree with you. How about adding macros or something like WARN_ON(XX_ARCH) or
> >>Kconfig to limit its scope?
> >
> >Thank you for giving me your idea.
> >Your suggestions above will work for me because I'm a x86 user.
> >If Tony agrees to it, I can update my patch.
> >
> >But, I'm hesitating to add WARN_ON() or change Kconfig only for specific arch
> >because pstore aims for generic interface and this is related to its design.
> >Also, ramoops is going to use pstore now. It doesn't depend on x86.
> >I'm worried that ramoops users will complain about this change.
> >
> >So, I think a reasonable solution at this time is just adding some explanations
> >about smp_send_stop() to documentation as follows.
> >
> >Users can use pstore with their own responsibility and ask developers
> >if smp_send_stop() is reliable enough in panic situation on architecture they want to run.
> >
> >What do you think?
> >
> >---
> > Documentation/ABI/testing/pstore | 8 ++++++++
> > 1 files changed, 8 insertions(+), 0 deletions(-)
> >
> >diff --git a/Documentation/ABI/testing/pstore b/Documentation/ABI/testing/pstore
> >index ff1df4e..5583729 100644
> >--- a/Documentation/ABI/testing/pstore
> >+++ b/Documentation/ABI/testing/pstore
> >@@ -11,6 +11,14 @@ Description: Generic interface to platform dependent persistent storage.
> > of the console log is captured, but other interesting
> > data can also be saved.
> >
> >+ In case of panic, pstore is invoked after smp_send_stop()
> >+ ,a function call stopping other cpus, so that we can get
> >+ logs simpler and cleaner with just one running cpu.
> >+
> >+ As for x86, smp_send_stop() is reliable enough to work in
> >+ panic situation. But we are not guaranteed that it works
> >+ reliably on other architectures.
> >+
> > # mount -t pstore -o kmsg_bytes=8000 - /dev/pstore
> >
> > $ ls -l /dev/pstore
>
> The explanation is great. but In my opinion, I still insist that
> a WARN_ON() is necessary. What do you think, Tony and Don?
I guess I still don't understand why. Who uses kmsg_dump besides x86? It
seems like there was only 3 or 4 subsystems that were registering.
Cheers,
Don
next prev parent reply other threads:[~2012-01-11 17:26 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-05 17:35 [RFC][PATCH v4 -next 0/4] Make pstore/kmsg_dump run after stopping other cpus in panic path Seiji Aguchi
2012-01-05 17:36 ` [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop() Seiji Aguchi
2012-01-05 19:06 ` Luck, Tony
2012-01-05 20:10 ` Seiji Aguchi
2012-01-05 21:01 ` Don Zickus
2012-01-09 17:59 ` Seiji Aguchi
2012-01-10 3:06 ` Chen Gong
2012-01-10 20:29 ` Seiji Aguchi
2012-01-11 7:28 ` Chen Gong
2012-01-11 17:25 ` Don Zickus [this message]
2012-01-11 22:22 ` Luck, Tony
2012-01-13 22:50 ` Seiji Aguchi
[not found] ` <32727E9A83EE9A42A1F0906295A3A77B2C78F49973@USINDEVS01.corp.hds.com>
2012-01-19 20:58 ` Seiji Aguchi
2012-01-20 17:56 ` Luck, Tony
2012-02-03 17:18 ` Don Zickus
2012-02-03 22:32 ` Luck, Tony
2012-02-03 22:57 ` Don Zickus
2012-02-08 20:19 ` Don Zickus
2012-02-08 21:28 ` Luck, Tony
2012-02-08 22:48 ` Don Zickus
2012-02-08 22:56 ` Seiji Aguchi
2012-01-05 17:38 ` [RFC][PATCH v4 -next 2/4] Skip spin_locks in panic case and Add WARN_ON() Seiji Aguchi
2012-01-05 17:39 ` [RFC][PATCH v4 -next 3/4]Skip subsequent kmsg_dump() function calls in panic path Seiji Aguchi
2012-01-05 17:41 ` [RFC][PATCH v4 -next 4/4] Skip spin_lock of efi_pstore_write() in panic case Seiji Aguchi
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