From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Sebastian Capella <sebastian.capella@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Russ Dill <Russ.Dill@ti.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
Nicolas Pitre <nico@linaro.org>,
Santosh Shilimkar <santosh.shilimkar@ti.com>,
Will Deacon <Will.Deacon@arm.com>,
Cyril Chemparathy <cyril@ti.com>,
Jonathan Austin <Jonathan.Austin@arm.com>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>,
Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk
Date: Sat, 22 Feb 2014 12:13:15 +0000 [thread overview]
Message-ID: <20140222121315.GB9012@e102568-lin.cambridge.arm.com> (raw)
In-Reply-To: <20140222101655.GE21483@n2100.arm.linux.org.uk>
On Sat, Feb 22, 2014 at 10:16:55AM +0000, Russell King - ARM Linux wrote:
> On Thu, Feb 20, 2014 at 04:27:55PM +0000, Lorenzo Pieralisi wrote:
> > I still do not understand why switching to idmap, which is a clone of
> > init_mm + 1:1 kernel mappings is required here. Why idmap ?
> >
> > And while at it, can't the idmap be overwritten _while_ copying back the
> > resume kernel ? Is it safe to use idmap page tables while copying ?
> >
> > I had a look at x86 and there idmap page tables used to resume are created
> > on the fly using safe pages, on ARM idmap is created at boot.
>
> That's fine.
>
> Remember, you're required to boot exactly the same kernel image when
> resuming as the kernel which created the suspend image. Unless you
> have random allocations going on, you should get the same layout for
> the idmap stuff at each boot.
Thanks Russell, now that's clear. We do need a copy of page tables
that are not tampered with while copying, and idmap works well for
that.
Lorenzo
WARNING: multiple messages have this Message-ID (diff)
From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk
Date: Sat, 22 Feb 2014 12:13:15 +0000 [thread overview]
Message-ID: <20140222121315.GB9012@e102568-lin.cambridge.arm.com> (raw)
In-Reply-To: <20140222101655.GE21483@n2100.arm.linux.org.uk>
On Sat, Feb 22, 2014 at 10:16:55AM +0000, Russell King - ARM Linux wrote:
> On Thu, Feb 20, 2014 at 04:27:55PM +0000, Lorenzo Pieralisi wrote:
> > I still do not understand why switching to idmap, which is a clone of
> > init_mm + 1:1 kernel mappings is required here. Why idmap ?
> >
> > And while at it, can't the idmap be overwritten _while_ copying back the
> > resume kernel ? Is it safe to use idmap page tables while copying ?
> >
> > I had a look at x86 and there idmap page tables used to resume are created
> > on the fly using safe pages, on ARM idmap is created at boot.
>
> That's fine.
>
> Remember, you're required to boot exactly the same kernel image when
> resuming as the kernel which created the suspend image. Unless you
> have random allocations going on, you should get the same layout for
> the idmap stuff at each boot.
Thanks Russell, now that's clear. We do need a copy of page tables
that are not tampered with while copying, and idmap works well for
that.
Lorenzo
next prev parent reply other threads:[~2014-02-22 12:13 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-19 1:52 [PATCH RFC v1 0/3] hibernation support on ARM Sebastian Capella
2014-02-19 1:52 ` Sebastian Capella
2014-02-19 1:52 ` [PATCH RFC v1 1/3] ARM: Add irq disabled version of soft_restart Sebastian Capella
2014-02-19 1:52 ` Sebastian Capella
2014-02-22 10:26 ` Russell King - ARM Linux
2014-02-22 10:26 ` Russell King - ARM Linux
2014-02-24 23:13 ` Sebastian Capella
2014-02-24 23:13 ` Sebastian Capella
2014-02-25 0:22 ` Sebastian Capella
2014-02-25 0:22 ` Sebastian Capella
2014-02-25 7:56 ` Russ Dill
2014-02-25 7:56 ` Russ Dill
2014-02-25 7:56 ` Russ Dill
2014-02-25 10:27 ` Thomas Gleixner
2014-02-25 10:27 ` Thomas Gleixner
2014-02-25 17:15 ` Russ Dill
2014-02-25 17:15 ` Russ Dill
2014-02-25 17:15 ` Russ Dill
2014-02-25 23:24 ` Sebastian Capella
2014-02-25 23:24 ` Sebastian Capella
2014-02-19 1:52 ` [PATCH RFC v1 2/3] Fix hibernation restore hang in freeze_processes Sebastian Capella
2014-02-19 1:52 ` Sebastian Capella
2014-02-24 7:09 ` Ming Lei
2014-02-24 7:09 ` Ming Lei
2014-02-19 1:52 ` [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk Sebastian Capella
2014-02-19 1:52 ` Sebastian Capella
2014-02-19 16:12 ` Lorenzo Pieralisi
2014-02-19 16:12 ` Lorenzo Pieralisi
2014-02-19 16:12 ` Lorenzo Pieralisi
2014-02-19 19:10 ` Russ Dill
2014-02-19 19:10 ` Russ Dill
2014-02-19 19:10 ` Russ Dill
2014-02-20 10:37 ` Lorenzo Pieralisi
2014-02-20 10:37 ` Lorenzo Pieralisi
2014-02-20 10:37 ` Lorenzo Pieralisi
2014-02-19 19:33 ` Sebastian Capella
2014-02-19 19:33 ` Sebastian Capella
2014-02-20 16:27 ` Lorenzo Pieralisi
2014-02-20 16:27 ` Lorenzo Pieralisi
2014-02-20 16:27 ` Lorenzo Pieralisi
2014-02-21 18:39 ` Sebastian Capella
2014-02-21 18:39 ` Sebastian Capella
2014-02-21 23:59 ` Sebastian Capella
2014-02-21 23:59 ` Sebastian Capella
2014-02-22 4:37 ` Sebastian Capella
2014-02-22 4:37 ` Sebastian Capella
2014-02-22 6:46 ` Russ Dill
2014-02-22 6:46 ` Russ Dill
2014-02-22 6:46 ` Russ Dill
2014-02-22 10:22 ` Russell King - ARM Linux
2014-02-22 10:22 ` Russell King - ARM Linux
2014-02-22 10:22 ` Russell King - ARM Linux
2014-02-22 10:16 ` Russell King - ARM Linux
2014-02-22 10:16 ` Russell King - ARM Linux
2014-02-22 10:16 ` Russell King - ARM Linux
2014-02-22 12:13 ` Lorenzo Pieralisi [this message]
2014-02-22 12:13 ` Lorenzo Pieralisi
2014-02-22 12:13 ` Lorenzo Pieralisi
2014-02-22 22:30 ` Pavel Machek
2014-02-22 22:30 ` Pavel Machek
2014-02-22 22:30 ` Pavel Machek
2014-02-21 1:01 ` Sebastian Capella
2014-02-21 1:01 ` Sebastian Capella
2014-02-22 10:38 ` Russell King - ARM Linux
2014-02-22 10:38 ` Russell King - ARM Linux
2014-02-22 10:38 ` Russell King - ARM Linux
2014-02-22 12:09 ` Lorenzo Pieralisi
2014-02-22 12:09 ` Lorenzo Pieralisi
2014-02-22 12:09 ` Lorenzo Pieralisi
2014-02-22 22:28 ` Pavel Machek
2014-02-22 22:28 ` Pavel Machek
2014-02-22 22:28 ` Pavel Machek
2014-02-23 19:52 ` Sebastian Capella
2014-02-23 19:52 ` Sebastian Capella
2014-02-23 19:52 ` Sebastian Capella
2014-02-23 20:02 ` Sebastian Capella
2014-02-23 20:02 ` Sebastian Capella
2014-02-23 20:02 ` Sebastian Capella
2014-02-25 11:32 ` Lorenzo Pieralisi
2014-02-25 11:32 ` Lorenzo Pieralisi
2014-02-25 11:32 ` Lorenzo Pieralisi
2014-02-25 17:55 ` Sebastian Capella
2014-02-25 17:55 ` Sebastian Capella
2014-02-26 10:24 ` Lorenzo Pieralisi
2014-02-26 10:24 ` Lorenzo Pieralisi
2014-02-26 10:24 ` Lorenzo Pieralisi
2014-02-26 17:50 ` Sebastian Capella
2014-02-26 17:50 ` Sebastian Capella
2014-02-26 19:03 ` Lorenzo Pieralisi
2014-02-26 19:03 ` Lorenzo Pieralisi
2014-02-26 19:03 ` Lorenzo Pieralisi
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