Message-ID: <47939363.8040603@kolumbus.fi>
Date: Sun, 20 Jan 2008 20:30:59 +0200
From: =?ISO-8859-1?Q?Mika_Penttil=E4?= <mika.penttila@kolumbus.fi>
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To: Ian Campbell <ijc@hellion.org.uk>
CC: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] x86: Construct 32 bit boot time page tables in native
 format.
References: <1200758937-22386-1-git-send-email-ijc@hellion.org.uk> <1200758937-22386-2-git-send-email-ijc@hellion.org.uk>
In-Reply-To: <1200758937-22386-2-git-send-email-ijc@hellion.org.uk>
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> + * This is how much memory *in addition to the memory covered up to
> + * and including _end* we need mapped initially.  We need one bit for
> + * each possible page, but only in low memory, which means
> + * 2^32/4096/8 = 128K worst case (4G/4G split.)
> + *
> + * Modulo rounding, each megabyte assigned here requires a kilobyte of
> + * memory, which is currently unreclaimed.
> + *
> + * This should be a multiple of a page.
> + */
> +#define INIT_MAP_BEYOND_END	(128*1024)
> +
> +/*
>   

You have dropped the requirement to map all of low memory (the boot 
allocator is used for instance to construct physical mem mapping). 
Either you should fix your INIT_MAP_BEYOND_END or make a big comment 
telling us why it isn't necessary anymore to map low mem.

--Mika
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