Re: [PATCH v2 1/4] x86, kdump: Set crashkernel_low automatically

[Vivek Goyal <vgoyal@redhat.com>]

On Wed, Apr 03, 2013 at 05:38:23PM -0700, Yinghai Lu wrote:

[..]
> +	if (ret != 0) {
> +		/*
> +		 * two parts from lib/swiotlb.c:
> +		 *	swiotlb size: user specified with swiotlb= or default.
> +		 *	swiotlb overflow buffer: now is hardcoded to 32k,
> +		 *		round to 8M to cover more others.
> +		 */
> +		low_size = swiotlb_size_or_default() + (8UL<<20);
> +		auto_set = true;

What is the correlation between swiotlb size of first kernel and second
kernel. They might be completely different kernel and with different
default size for swiotlb buffers.

[..]
>  
> +	crashkernel_low=size[KMG]
> +			[KNL, x86_64] range under 4G. When crashkernel= is
> +			passed, kernel allocate physical memory region
> +			above 4G,
	
This is not right. "When crashkernel=X;high is passed kernel first tries
to allocate memory above 4G". crashkernel=X does not try to allocate 
memory above 4G.

Vivek