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From: Valdis.Kletnieks@vt.edu
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
ak@muc.de, ebiederm@xmission.com, rdreier@cisco.com,
gregkh@suse.de, airlied@skynet.ie, davej@redhat.com,
mingo@elte.hu, tglx@linutronix.de, akpm@linux-foundation.org,
arjan@infradead.org, "Barnes, Jesse" <jesse.barnes@intel.com>,
davem@davemloft.net, linux-kernel@vger.kernel.org, "Siddha,
Suresh B" <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 17:50:41 -0500 [thread overview]
Message-ID: <11912.1200005441@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Thu, 10 Jan 2008 14:15:25 PST." <alpine.LFD.1.00.0801101413490.3148@woody.linux-foundation.org>
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On Thu, 10 Jan 2008 14:15:25 PST, Linus Torvalds said:
> Well, I think that /dev/mem should simply give them the right info. That's
> what people use /dev/mem for - doing things like reading BIOS images etc.
>
> So returning *either* a zero page *or* stopping at the first hole is both
> equally wrong.
A case could be made that the /dev/mem driver should at *least* prohibit access
to those memory ranges that the kernel already knows have (or might have)
memory-mapped control registers with Bad Juju side-effects attached to them.
Of course, a case could also be made that it should be permitted, because
anybody who tries to read such memory addresses either (a) knows what they're
doing or (b) is about to become an example of evolution in action... ;)
(Personally, I keep a copy of Arjan's "restrict devmem" patch from Fedora
around, so I guess that says which camp I belong in, and the fact it's a Fedora
patch and not mainstream says something too...)
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next prev parent reply other threads:[~2008-01-10 22:53 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
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 [this message]
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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