From: Andi Kleen <ak@suse.de>
To: Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [patch] Ignore MCFG if the mmconfig area isn't reserved in the e820 table
Date: Thu, 23 Mar 2006 18:56:11 +0100
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On Thursday 23 March 2006 19:22, Arjan van de Ven wrote:
> Hi,
> 
> There have been several machines that don't have a working MMCONFIG,
> often because of a buggy MCFG table in the ACPI bios. This patch adds a
> simple sanity check that detects a whole bunch of these cases, and when
> it detects it, linux now boots rather than crash-and-burns. 

Yes, MCFG is a pain recently. Looks like we did the grave mistake
of using something in the BIOS before Windows again.

> +
> +/*
> + * Check if an address is reserved in the e820 map
> + */
> +int is_e820_reserved(u64 address)
> +{
> +	int	      i;
> +	i = e820.nr_map;
> +	while (--i >= 0) {
> +		unsigned long long start = e820.map[i].addr;
> +		unsigned long long end = start + e820.map[i].size;
> +
> +		if (address <=end && address >= start) {
> +			if (e820.map[i].type == E820_RESERVED)
> +				return 1;
> +			else
> +				return 0;
> +		}
> +	}
> +	return 0;
> +}

That is e820_mapped(address, address+size, E820_RESERVED)

And not having a size is definitely wrong on i386 too.

-Andi

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