From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jun Sun <jsun@junsun.net>
Cc: "Richard B. Johnson" <jmodem@abominablefirebug.com>,
linux-kernel@vger.kernel.org
Subject: Re: reserve memory in low physical address - possible?
Date: Tue, 31 Oct 2006 16:01:10 +0000 [thread overview]
Message-ID: <1162310470.11965.79.camel@localhost.localdomain> (raw)
In-Reply-To: <20061031154019.GC14272@srv.junsun.net>
Ar Maw, 2006-10-31 am 07:40 -0800, ysgrifennodd Jun Sun:
> On Tue, Oct 31, 2006 at 07:32:37AM -0500, Richard B. Johnson wrote:
> >
> > You will not be able to reserve any address space starting at 0 anyway, but
> > your driver or even
> > user-space code can memory-map it.
> >
>
> Any reasons or concerns as to why I can't reserve any address space
> starting from 0?
None at all, Richard is wrong on this point. You can happily reserve
memory starting at physical zero on an x86. In fact the x86 kernel
*already* does this because many BIOSes use the first page for BIOS data
and touch it when we use BIOS services or in SMM.
For a worked example of loading Linux under a small RTOS take a look at
RTLinux, which turns Linux into on task running on a tiny strict RT
kernel.
Alan
next prev parent reply other threads:[~2006-10-31 15:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-31 7:22 reserve memory in low physical address - possible? Jun Sun
2006-10-31 8:12 ` Paul Mundt
2006-10-31 15:06 ` Jun Sun
2006-11-02 18:40 ` Jun Sun
2006-10-31 12:32 ` Richard B. Johnson
2006-10-31 15:40 ` Jun Sun
2006-10-31 16:01 ` Alan Cox [this message]
2006-10-31 12:45 ` Mark Hounschell
2006-10-31 15:14 ` Jun Sun
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