Date: Sat, 3 Dec 2005 10:06:32 +0100
From: Willy Tarreau <willy@w.ods.org>
To: Daniel Bonekeeper <thehazard@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: kernel loading question
Message-ID: <20051203090632.GC22139@alpha.home.local>
References: <e1e1d5f40512022134y73318ed4p54064a07905cef3c@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <e1e1d5f40512022134y73318ed4p54064a07905cef3c@mail.gmail.com>
User-Agent: Mutt/1.5.10i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1279
Lines: 30

On Fri, Dec 02, 2005 at 09:34:26PM -0800, Daniel Bonekeeper wrote:
> Well, this probably should not be posted here, but who knows ? =)
> 
> Well, on arch/i386/boot/compressed/head.S line 65 we call
> decompress_kernel that decompresses the kernel starting at $0x100000.
> If we were loaded high, we first move the code back to $0x1000 before
> ljmp'ing it.
> 
> My question is: why, when loaded high, we care to disable interrupts
> (cli  # make sure we don't get interrupted) while otherwise, we don't
> do that ? in both cases, aren't we supposed to disable cli (as they
> can happen in both situations) ?
> 
> Since currently, the kernel boots fine for everybody in the world, I
> know that this is not a bug... but why don't disable interruptions on
> both cases ?

Agreed it's strange. I believe that since very few people load the
kernel in low memory nowadays given its size, it's possible that the
missing CLI never gets noticed, and I suspect that the very first
instructions after the jump are a CLI anyway.

Regards,
Willy

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/