From: Andi Kleen <andi@firstfloor.org>
To: Yoav Artzi <yoavar@checkpoint.com>
Cc: Andi Kleen <andi@firstfloor.org>, linux-kernel@vger.kernel.org
Subject: Re: Linux kernel memory and split on 64-bit machines
Date: Mon, 29 Oct 2007 16:48:01 +0100 [thread overview]
Message-ID: <20071029154801.GA31335@one.firstfloor.org> (raw)
In-Reply-To: <4725F6F7.6020702@checkpoint.com>
On Mon, Oct 29, 2007 at 05:06:31PM +0200, Yoav Artzi wrote:
> I don't know what befell me. I realized the foolishness of the questions
> a second after clicking the send button.
>
>
> Now, I just wonder what will happen when people will need more then
> 2^46bytes of memory. Any idea?
The CPU needs to be extended then beyond 48bit VA.
(actually it could be extended to 2^46.5 or so)
>
> Another two issues:
>
> 1. I see vmalloc() doesn't cover the entire possible space. Why is that?
It needs an reserved space for its virtual mappings.
>
> 2. How come user space gets 47bits and kernel only gets 46bits in direct
> mapping?
Half of the kernel space is reserved for special purposes
(vmalloc, ioremap etc.) That is not fixed and could be varied.
-Andi
prev parent reply other threads:[~2007-10-29 15:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-29 11:20 Linux kernel memory and split on 64-bit machines Yoav Artzi
2007-10-29 12:11 ` Andi Kleen
[not found] ` <4725EC21.7000603@checkpoint.com>
[not found] ` <20071029150035.GA30851@one.firstfloor.org>
[not found] ` <4725F6F7.6020702@checkpoint.com>
2007-10-29 15:48 ` Andi Kleen [this message]
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