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From: Santosh Shilimkar <santosh.shilimkar@ti.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	linux-mips <linux-mips@linux-mips.org>,
	Aurelien Jacquiot <a-jacquiot@ti.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Paul Mackerras <paulus@samba.org>,
	Jonas Bonn <jonas@southpole.se>,
	Russell King <linux@arm.linux.org.uk>,
	<linux-c6x-dev@linux-c6x.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	"arm@kernel.org" <arm@kernel.org>,
	Rob Herring <robherring2@gmail.com>,
	Grant Likely <grant.likely@linaro.org>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
	<linux-xtensa@linux-xtensa.org>,
	James Hogan <james.hogan@imgtec.com>,
	devicetree-discuss <devicetree-discuss@lists.ozlabs.org>,
	Rob Herring <rob.herring@calxeda.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Chris Zankel <chris@zankel.net>,
	Vineet Gupta <vgupta@synopsys.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ralf Baechle <ralf@linux-mips.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] of: Specify initrd location using 64-bit
Date: Mon, 1 Jul 2013 09:58:35 -0400	[thread overview]
Message-ID: <51D18B0B.1060906@ti.com> (raw)
In-Reply-To: <CAMuHMdV6YM3-hASqjxkguEukZjnjK80gBjDNiabxjfQtC=c8ag@mail.gmail.com>

On Monday 01 July 2013 03:59 AM, Geert Uytterhoeven wrote:
> On Mon, Jul 1, 2013 at 9:48 AM, Sebastian Andrzej Siewior
> <bigeasy@linutronix.de> wrote:
>> On 06/29/2013 01:43 AM, Santosh Shilimkar wrote:
>>> Apart from waste of 32bit, what is the other concern you
>>> have ?
>>
>> You pass a u64 as a physical address which is represented in other
>> parts of the kernel (for a good reason) by phys_addr_t.
>>
>>> I really want to converge on this patch because it
>>> has been a open ended discussion for quite some time. Does
>>> that really break any thing on x86 or your concern is more
>>> from semantics of the physical address.
>> You want to have your code in so you can continue with your work, that
>> is okay. The other two arguments why u64 here is a good thing was "due
>> to what I said earlier" and "+1" and I don't have the time to look
>> that up.
>>
>> There should be no problems on x86 if this goes in as it is now.
>>
>> But think about this: What happens if you boot your ARM device without
>> PAE and your initrd is in the upper region? If you are lucky the kernel
>> looks at a different place where it also has a read permission, notices
>> nothing sane is there, writes a message and continues. And if it is not
>> allowed to read? It is clearly the user's fault for booting a non-PAE
>> kernel.
> 
> That's actual the original reason: DT has it as 64 bit, and passes it to a
> 32 bit kernel when running in 32 bit mode without PAE.
> 
Thanks all for comments and useful discussion. I will resubmit the
patch with update to fix the printk warnings reported by Vineet and
James post the $subject change.

Am assuming the patch will go via Grant Likely's tree.

Regards,
Santosh

WARNING: multiple messages have this Message-ID (diff)
From: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	linux-mips <linux-mips@linux-mips.org>,
	Aurelien Jacquiot <a-jacquiot@ti.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Paul Mackerras <paulus@samba.org>,
	Jonas Bonn <jonas@southpole.se>,
	Russell King <linux@arm.linux.org.uk>,
	linux-c6x-dev@linux-c6x.org,
	the arch/x86 maintainers <x86@kernel.org>,
	"arm@kernel.org" <arm@kernel.org>,
	Rob Herring <robherring2@gmail.com>,
	Grant Likely <grant.likely@linaro.org>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
	linux-xtensa@linux-xtensa.org,
	James Hogan <james.hogan@imgtec.com>,
	devicetree-discuss <devicetree-discuss@lists.ozlabs.org>,
	Rob Herring <rob.herring@calxeda.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Chris Zankel <chris@zankel.net>,
	Vineet Gupta <vgupta@synopsys.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ralf Baechle <ralf@linux-mips.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] of: Specify initrd location using 64-bit
Date: Mon, 1 Jul 2013 09:58:35 -0400	[thread overview]
Message-ID: <51D18B0B.1060906@ti.com> (raw)
Message-ID: <20130701135835.5Lso_A1KFoGgP3IdWChiw9VLVy_RY2-8IqZ9qbfcKAY@z> (raw)
In-Reply-To: <CAMuHMdV6YM3-hASqjxkguEukZjnjK80gBjDNiabxjfQtC=c8ag@mail.gmail.com>

On Monday 01 July 2013 03:59 AM, Geert Uytterhoeven wrote:
> On Mon, Jul 1, 2013 at 9:48 AM, Sebastian Andrzej Siewior
> <bigeasy@linutronix.de> wrote:
>> On 06/29/2013 01:43 AM, Santosh Shilimkar wrote:
>>> Apart from waste of 32bit, what is the other concern you
>>> have ?
>>
>> You pass a u64 as a physical address which is represented in other
>> parts of the kernel (for a good reason) by phys_addr_t.
>>
>>> I really want to converge on this patch because it
>>> has been a open ended discussion for quite some time. Does
>>> that really break any thing on x86 or your concern is more
>>> from semantics of the physical address.
>> You want to have your code in so you can continue with your work, that
>> is okay. The other two arguments why u64 here is a good thing was "due
>> to what I said earlier" and "+1" and I don't have the time to look
>> that up.
>>
>> There should be no problems on x86 if this goes in as it is now.
>>
>> But think about this: What happens if you boot your ARM device without
>> PAE and your initrd is in the upper region? If you are lucky the kernel
>> looks at a different place where it also has a read permission, notices
>> nothing sane is there, writes a message and continues. And if it is not
>> allowed to read? It is clearly the user's fault for booting a non-PAE
>> kernel.
> 
> That's actual the original reason: DT has it as 64 bit, and passes it to a
> 32 bit kernel when running in 32 bit mode without PAE.
> 
Thanks all for comments and useful discussion. I will resubmit the
patch with update to fix the printk warnings reported by Vineet and
James post the $subject change.

Am assuming the patch will go via Grant Likely's tree.

Regards,
Santosh

  parent reply	other threads:[~2013-07-01 13:59 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-21  0:52 [PATCH] of: Specify initrd location using 64-bit Santosh Shilimkar
2013-06-21  0:52 ` Santosh Shilimkar
2013-06-21  4:39 ` Vineet Gupta
2013-06-21  4:39   ` Vineet Gupta
2013-06-21  8:23   ` James Hogan
2013-06-21  8:23     ` James Hogan
2013-06-21 17:12     ` Santosh Shilimkar
2013-06-21 17:12       ` Santosh Shilimkar
2013-06-21  9:04 ` Sebastian Andrzej Siewior
2013-06-21 17:20   ` Santosh Shilimkar
2013-06-21 17:20     ` Santosh Shilimkar
2013-06-27 20:54     ` Rob Herring
2013-06-28  7:54       ` Sebastian Andrzej Siewior
2013-06-28  9:59       ` Grant Likely
2013-06-28  9:59         ` Grant Likely
2013-06-28 13:49         ` Jean-Christophe PLAGNIOL-VILLARD
2013-06-28 13:49           ` Jean-Christophe PLAGNIOL-VILLARD
2013-06-28 23:43           ` Santosh Shilimkar
2013-06-28 23:43             ` Santosh Shilimkar
2013-06-29  8:34             ` Geert Uytterhoeven
2013-06-29  8:34               ` Geert Uytterhoeven
2013-07-01  7:48             ` Sebastian Andrzej Siewior
2013-07-01  7:48               ` Sebastian Andrzej Siewior
2013-07-01  7:59               ` Geert Uytterhoeven
2013-07-01  7:59                 ` Geert Uytterhoeven
2013-07-01  8:09                 ` Sebastian Andrzej Siewior
2013-07-01  8:09                   ` Sebastian Andrzej Siewior
2013-07-01 13:58                 ` Santosh Shilimkar [this message]
2013-07-01 13:58                   ` Santosh Shilimkar
  -- strict thread matches above, loose matches on Subject: below --
2012-09-12 16:05 [PATCH] of: specify " Cyril Chemparathy
2012-09-12 16:05 ` Cyril Chemparathy
2012-09-12 16:16 ` Geert Uytterhoeven
2012-09-12 18:02   ` Cyril Chemparathy
2012-09-12 18:02     ` Cyril Chemparathy
2012-09-12 19:58     ` Sebastian Andrzej Siewior
2012-09-12 22:08       ` Rob Herring
2012-09-13  6:47         ` Sebastian Andrzej Siewior
2012-09-13 21:02           ` Rob Herring
2012-09-12 20:23 ` Rob Herring
2012-09-12 20:31   ` Nicolas Pitre
2012-09-12 20:56     ` Rob Herring
2012-09-12 23:45   ` Cyril Chemparathy
2012-09-12 23:45     ` Cyril Chemparathy

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