[PATCH 1/2] kdump/x86: crashkernel=X try to reserve below 896M first then below 4G and MAXMEM

[Dave Young]

Hi,
 
This is a resend of below patches:
http://lists.infradead.org/pipermail/kexec/2017-October/019569.html
 
I dropped the original patch 1 since Baoquan is not happy with it.
For patch 2 (the 1st patch in this series), there is some improvement
comment from Baoquan to create some generic memblock iteration function.
But nobody has time to work on it for the time being.  According to
offline discussion with him.  That can be done in the future if someone
is interested.  We can go with the current kdump only fixes.
 
Other than above,  the patches are just same.
 
Thanks
Dave