From: "H. Peter Anvin" <hpa@kernel.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jan Beulich <jbeulich@novell.com>, Ingo Molnar <mingo@elte.hu>,
Andi Kleen <andi@firstfloor.org>,
Stable Kernel <stable@kernel.org>,
x86@kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: set PAE PHYSICAL_MASK_SHIFT to match 64-bit
Date: Sat, 07 Jun 2008 11:39:25 -0700 [thread overview]
Message-ID: <484AD5DD.9040403@kernel.org> (raw)
In-Reply-To: <4848F233.10008@goop.org>
Jeremy Fitzhardinge wrote:
>>
>> No, it's the fact that the 1:1 mapping needs as much virtual space as
>> the physical range covered (including all holes).
>
> Right, I see. And suddenly 64-bits seems... constrained. ;)
>
Not really. The vendors are aware of this constraint -- it's hardly
unique to Linux. The reason for canonical addresses and all that jazz
is to keep people from doing stupid things like store stuff in the upper
16 bits of a pointer (happened a lot on the 68000, where the first
implementation had only 24 address bits.) Thus, all changes needed to
go to a larger virtual address space are all internal to the kernel.
-hpa
next prev parent reply other threads:[~2008-06-07 18:43 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-05 15:21 [PATCH] x86: set PAE PHYSICAL_MASK_SHIFT to match 64-bit Jeremy Fitzhardinge
2008-06-05 15:34 ` Jan Beulich
2008-06-05 15:42 ` Jeremy Fitzhardinge
2008-06-05 16:45 ` H. Peter Anvin
2008-06-05 21:14 ` Jeremy Fitzhardinge
2008-06-07 18:35 ` H. Peter Anvin
2008-06-06 9:21 ` [PATCH UPDATED] x86: set PAE PHYSICAL_MASK_SHIFT to 44 bits Jeremy Fitzhardinge
2008-06-06 9:58 ` Jan Beulich
2008-06-06 13:15 ` Andi Kleen
2008-06-06 13:50 ` Jeremy Fitzhardinge
2008-06-10 10:31 ` Ingo Molnar
2008-06-10 13:06 ` Jeremy Fitzhardinge
2008-06-13 7:24 ` Ingo Molnar
2008-06-06 1:40 ` [PATCH] x86: set PAE PHYSICAL_MASK_SHIFT to match 64-bit Andi Kleen
2008-06-06 7:14 ` Jan Beulich
2008-06-06 7:59 ` Jeremy Fitzhardinge
2008-06-06 8:14 ` Jan Beulich
2008-06-06 8:15 ` Jeremy Fitzhardinge
2008-06-07 18:39 ` H. Peter Anvin [this message]
2008-06-06 4:45 ` Arjan van de Ven
2008-06-06 8:08 ` Jeremy Fitzhardinge
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