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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: ak@muc.de, ebiederm@xmission.com, rdreier@cisco.com,
	gregkh@suse.de, airlied@skynet.ie, davej@redhat.com,
	mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com,
	akpm@linux-foundation.org, arjan@infradead.org,
	jesse.barnes@intel.com, davem@davemloft.net,
	linux-kernel@vger.kernel.org,
	Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [patch 02/11] PAT x86: Map only usable memory in x86_64 identity map and kernel text
Date: Thu, 10 Jan 2008 13:05:08 -0800 (PST)	[thread overview]
Message-ID: <alpine.LFD.1.00.0801101303570.3148@woody.linux-foundation.org> (raw)
In-Reply-To: <20080110184854.787474000@intel.com>



On Thu, 10 Jan 2008, venkatesh.pallipadi@intel.com wrote:
>
> x86_64: Map only usable memory in identity map. All reserved memory maps to a
> zero page.

I don't mind this horribly per se, but why a zero page?

Accessing that page without mapping it explicitly would be a bug with 
your change - if only because you'd get the wrong value!

So why map it at all? The only thing mapping it can do is to hide bugs.

			Linus

  parent reply	other threads:[~2008-01-10 21:11 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-10 18:48 [patch 00/11] PAT x86: PAT support for x86 venkatesh.pallipadi
2008-01-10 18:48 ` [patch 01/11] PAT x86: Make acpi/other drivers map memory instead of assuming identity map venkatesh.pallipadi
2008-01-10 18:48 ` [patch 02/11] PAT x86: Map only usable memory in x86_64 identity map and kernel text venkatesh.pallipadi
2008-01-10 19:06   ` Andi Kleen
2008-01-10 19:17     ` Pallipadi, Venkatesh
2008-01-10 19:28       ` Andi Kleen
2008-01-10 20:50         ` Pallipadi, Venkatesh
2008-01-10 21:16           ` Andi Kleen
2008-01-10 22:25             ` Pallipadi, Venkatesh
2008-01-10 22:35               ` Andi Kleen
2008-01-14 16:43           ` Ingo Molnar
2008-01-14 21:21             ` Siddha, Suresh B
2008-01-14 21:28               ` Andi Kleen
2008-01-15 22:17               ` Ingo Molnar
2008-01-15 23:11                 ` Andi Kleen
2008-01-15 23:21                 ` Siddha, Suresh B
2008-01-18 12:01                   ` Ingo Molnar
2008-01-18 13:12                     ` Andi Kleen
2008-01-18 16:46                       ` Jesse Barnes
2008-01-18 18:12                         ` Andi Kleen
2008-01-18 19:02                           ` Jesse Barnes
2008-01-19  2:42                             ` Andi Kleen
2008-01-10 21:05   ` Linus Torvalds [this message]
2008-01-10 21:57     ` Pallipadi, Venkatesh
2008-01-10 22:15       ` Linus Torvalds
2008-01-10 22:27         ` Pallipadi, Venkatesh
2008-01-10 22:50         ` Valdis.Kletnieks
2008-01-18 18:27           ` Dave Jones
2008-01-18 20:54             ` Ingo Molnar
2008-01-10 18:48 ` [patch 03/11] PAT x86: Map only usable memory in i386 identity map venkatesh.pallipadi
2008-01-10 19:10   ` Andi Kleen
2008-01-10 18:48 ` [patch 04/11] PAT x86: Basic PAT implementation venkatesh.pallipadi
2008-01-10 18:48 ` [patch 05/11] PAT x86: drm driver changes for PAT venkatesh.pallipadi
2008-01-10 18:48 ` [patch 06/11] PAT x86: Refactoring i386 cpa venkatesh.pallipadi
2008-01-10 19:00   ` Andi Kleen
2008-01-14 16:47     ` Ingo Molnar
2008-01-10 18:48 ` [patch 07/11] PAT x86: pat-conflict resolution using linear list venkatesh.pallipadi
2008-01-10 19:13   ` Andi Kleen
2008-01-10 20:08     ` Pallipadi, Venkatesh
2008-01-10 18:48 ` [patch 08/11] PAT x86: pci mmap conlfict patch venkatesh.pallipadi
2008-01-10 18:48 ` [patch 09/11] PAT x86: Add ioremap_wc support venkatesh.pallipadi
2008-01-10 19:08   ` Andi Kleen
2008-01-10 19:25     ` Pallipadi, Venkatesh
2008-01-12  0:18       ` Roland Dreier
2008-01-10 18:48 ` [patch 10/11] PAT x86: Handle /dev/mem mappings venkatesh.pallipadi
2008-01-10 18:48 ` [patch 11/11] PAT x86: Expose uc and wc interfaces in /sysfs vor pci_mmap_resource venkatesh.pallipadi
2008-01-10 19:43   ` Greg KH
2008-01-10 20:54     ` [patch 11/11] PAT x86: Expose uc and wc interfaces in /sysfsvor pci_mmap_resource Pallipadi, Venkatesh

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