[elrepo] How to understand elrepo kernel config changes

[Chengwei Yang]

Hi there,

I'm new to elrepo and I found that the goal of elrepo is exactly the same as me.

I checked kernel-lt and found that it brings a config file which I curious a lot
how to understand what it does, because I found there are a lot of changes from
centos 3.10.0 kernel config.

I did below to check config changes:

```
[root at linux-4.4.186]# cp /boot/config-3.10.0-693.21.1.el7.x86_64 .config
[root at linux-4.4.186]# make -s ARCH=x86_64 listnewconfig | wc -l
.config:3082:warning: symbol value 'm' invalid for PINCTRL_AMD
506
```

so there are 506 new changes.

I make all new changes as default configs.

```
[root at linux-4.4.186]# make -s ARCH=x86_64 alldefconfig
[root at linux-4.4.186]# make -s ARCH=x86_64 listnewconfig |wc -l
0
```

and then check the diff.

```
[root at linux-4.4.186]# diff -u .config config-4.4.186-x86_64 |wc -l
7712
```

There are a lot of changes from default configs, please help me to understand
what config-4.4.186-x86_64 changes.

-- 
Thanks,
Chengwei