[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <YoSijKwuwbY9uHxG@alley>
Date: Wed, 18 May 2022 09:38:52 +0200
From: Petr Mladek <pmladek@...e.com>
To: "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc: Scott Branden <scott.branden@...adcom.com>,
Sebastian Reichel <sre@...nel.org>,
Florian Fainelli <f.fainelli@...il.com>,
David Gow <davidgow@...gle.com>,
Evan Green <evgreen@...omium.org>,
Julius Werner <jwerner@...omium.org>,
bcm-kernel-feedback-list@...adcom.com, linux-pm@...r.kernel.org,
akpm@...ux-foundation.org, bhe@...hat.com,
kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, linux-alpha@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-edac@...r.kernel.org,
linux-hyperv@...r.kernel.org, linux-leds@...r.kernel.org,
linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
linux-remoteproc@...r.kernel.org, linux-s390@...r.kernel.org,
linux-tegra@...r.kernel.org, linux-um@...ts.infradead.org,
linux-xtensa@...ux-xtensa.org, netdev@...r.kernel.org,
openipmi-developer@...ts.sourceforge.net, rcu@...r.kernel.org,
sparclinux@...r.kernel.org, xen-devel@...ts.xenproject.org,
x86@...nel.org, kernel-dev@...lia.com, kernel@...ccoli.net,
halves@...onical.com, fabiomirmar@...il.com,
alejandro.j.jimenez@...cle.com, andriy.shevchenko@...ux.intel.com,
arnd@...db.de, bp@...en8.de, corbet@....net,
d.hatayama@...fujitsu.com, dave.hansen@...ux.intel.com,
dyoung@...hat.com, feng.tang@...el.com, gregkh@...uxfoundation.org,
mikelley@...rosoft.com, hidehiro.kawai.ez@...achi.com,
jgross@...e.com, john.ogness@...utronix.de, keescook@...omium.org,
luto@...nel.org, mhiramat@...nel.org, mingo@...hat.com,
paulmck@...nel.org, peterz@...radead.org, rostedt@...dmis.org,
senozhatsky@...omium.org, stern@...land.harvard.edu,
tglx@...utronix.de, vgoyal@...hat.com, vkuznets@...hat.com,
will@...nel.org, Alexander Gordeev <agordeev@...ux.ibm.com>,
Andrea Parri <parri.andrea@...il.com>,
Ard Biesheuvel <ardb@...nel.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Brian Norris <computersforpeace@...il.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
"David S. Miller" <davem@...emloft.net>,
Dexuan Cui <decui@...rosoft.com>,
Doug Berger <opendmb@...il.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Hari Bathini <hbathini@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Justin Chen <justinpopo6@...il.com>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Lee Jones <lee.jones@...aro.org>,
Markus Mayer <mmayer@...adcom.com>,
Michael Ellerman <mpe@...erman.id.au>,
Mihai Carabas <mihai.carabas@...cle.com>,
Nicholas Piggin <npiggin@...il.com>,
Paul Mackerras <paulus@...ba.org>, Pavel Machek <pavel@....cz>,
Shile Zhang <shile.zhang@...ux.alibaba.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Tianyu Lan <Tianyu.Lan@...rosoft.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Wang ShaoBo <bobo.shaobowang@...wei.com>,
Wei Liu <wei.liu@...nel.org>,
zhenwei pi <pizhenwei@...edance.com>
Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list
On Tue 2022-05-17 13:42:06, Guilherme G. Piccoli wrote:
> On 17/05/2022 10:57, Petr Mladek wrote:
> >> Disagree here, I'm CCing Florian for information.
> >>
> >> This notifier preserves RAM so it's *very interesting* if we have
> >> kmsg_dump() for example, but maybe might be also relevant in case kdump
> >> kernel is configured to store something in a persistent RAM (then,
> >> without this notifier, after kdump reboots the system data would be lost).
> >
> > I see. It is actually similar problem as with
> > drivers/firmware/google/gsmi.c.
> >
> > I does similar things like kmsg_dump() so it should be called in
> > the same location (after info notifier list and before kdump).
> >
> > A solution might be to put it at these notifiers at the very
> > end of the "info" list or make extra "dump" notifier list.
>
> Here I still disagree. I've commented in the other response thread
> (about Google gsmi) about the semantics of the hypervisor list, but
> again: this list should contain callbacks that
>
> (a) Should run early, _by default_ before a kdump;
> (b) Communicate with the firmware/hypervisor in a "low-risk" way;
>
> Imagine a scenario where users configure kdump kernel to save something
> in a persistent form in DRAM - it'd be like a late pstore, in the next
> kernel. This callback enables that, it's meant to inform FW "hey, panic
> happened, please from now on don't clear the RAM in the next FW-reboot".
> I don't see a reason to postpone that - let's see if the maintainers
> have an opinion.
I have answered this in more detail in the other reply, see
https://lore.kernel.org/r/YoShZVYNAdvvjb7z@alley
I agree that both notifiers in
drivers/soc/bcm/brcmstb/pm/pm-arm.c
drivers/firmware/google/gsmi.c
better fit into the hypervisor list after all.
Best Regards,
Petr
Powered by blists - more mailing lists