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

From: Vivek Goyal
Date: Thu Apr 04 2013 - 10:11:38 EST


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
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