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Date: Thu, 6 Mar 2003 22:26:07 +0100
From: Pavel Machek <pavel@ucw.cz>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Reserving physical memory at boot time
Message-ID: <20030306212607.GA173@elf.ucw.cz>
References: <Pine.LNX.3.95.1021204115837.29419B-100000@chaos.analogic.com> <Pine.LNX.4.33L2.0212040905230.8842-100000@dragon.pdx.osdl.net> <b442s0$pau$1@cesium.transmeta.com> <32981.4.64.238.61.1046844111.squirrel@www.osdl.org> <b453mj$qpi$1@cesium.transmeta.com>
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Hi!

> > OK, with feeling:
> > 
> > I agree with you since the boot protocol is well-defined.
> > 
> > Just to be clear, my comment was referring to
> > Documentation/kernel-parameters.txt, not to any C code.
> > 
> > And it would really be helpful to catch issues like this soon
> > after they happen...
> > 
> 
> Unfortunately last time I commented on this the response was roughly
> "well, the patch already made it into Linus' kernel, it's too late to
> fix it now."  That isn't exactly a very helpful response.
> 
> The mem= parameter has the semantic in the i386/PC boot protocol that
> it specifies the top address of the usable memory region that begins
> at 0x100000.  It's a bit of a wart that the boot loaders have to be
> aware of this, but it's so and it's been so for a very long time.

Really? So user has to know where ACPI tables are and specify less
than that on mem= command line? That seems very
counter-intuitive. [Ahha, its probaly okay because e820 saves you.]

What do you pass on 4GB machine as mem= parameter? AFAIK those beasts
have hole at 3.75G. [Hopefully bigmem machines have working e820
tables?]

								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
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