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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
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 10:16:55 +0000	[thread overview]
Message-ID: <20140222101655.GE21483@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20140220162754.GC15994@e102568-lin.cambridge.arm.com>

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.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".

WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk
Date: Sat, 22 Feb 2014 10:16:55 +0000	[thread overview]
Message-ID: <20140222101655.GE21483@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20140220162754.GC15994@e102568-lin.cambridge.arm.com>

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.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".

  parent reply	other threads:[~2014-02-22 10:17 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 [this message]
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
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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