小言
这篇文章的初衷是前2天写的文章[Linux]CentOS7.6更新内核中使用了ELRepo，而在那篇文章说到这个ELRepo是个内核源，因为那篇文章是关于内核升级的。但是现在一想来总觉得不太对，就有这篇文章记录一下
ELRepo介绍
先贴个官网说明【官网】
“For the community, by the community.”
Welcome to ELRepo, an RPM repository for Enterprise Linux packages. ELRepo supports Red Hat Enterprise Linux (RHEL) and its derivatives (Scientific Linux, CentOS & others).
The ELRepo Project focuses on hardware related packages to enhance your experience with Enterprise Linux. This includes filesystem drivers, graphics drivers, network drivers, sound drivers, webcam and video drivers.
For the community, by the community. 这句话相当的棒！！
整段话大概的意思就是说ELRepo是一个企业级Linux工具包的RPM仓库，ELRepo支持RedHat企业级Linux系统以及它的衍生产品。
那ELRepo关注怎样的工具包呢？它主要关注一些与硬件相关工具包，用于提升Linux的用户体验。其中包括文件系统驱动，图形驱动，网络驱动，声音驱动，摄像头及视频驱动等。
ELRepo的内容
再贴官方引用
ELRepo contains four channels. You can browse the contents of each channel by clicking on its name.
elrepo
This is the main channel and is enabled by default. As this channel should not contain packages also present in the distribution, it should be safe to run a ‘yum update’ with this repository channel enabled.
For example, to install kmod-r8168 (Realtek r8168 NIC driver):yum install kmod-r8168
Depending on the package being installed or the repository setup, it might be necessary to disable non-elrepo repositories:yum --disablerepo=\* --enablerepo=elrepo install kmod-nvidia
elrepo-extras
The elrepo-extras channel provides packages and their dependencies that replace/update RHEL distribution packages. It may be enabled in the /etc/yum.repos.d/elrepo.repo file or used with ‘yum –enablerepo=elrepo-extras’.
elrepo-testing
The elrepo-testing channel provides packages yet to be released to the main channel and is disabled by default. It may be enabled in the /etc/yum.repos.d/elrepo.repo file or used with ‘yum –enablerepo=elrepo-testing’.
elrepo-kernel
The elrepo-kernel channel provides both the long-term support kernels (which have been configured for RHEL-7 and RHEL-6) and the latest stable mainline kernels (which have been configured for RHEL-7) using sources available from the Linux Kernel Archives (external link). Please see the kernel-lt or kernel-ml pages for further details. This channel may be enabled in the /etc/yum.repos.d/elrepo.repo file or used with ‘yum –enablerepo=elrepo-kernel’.
这几段话主要说的是
ELRepo呢，共包含4个模块：elrepo、elrepo-extra、elrepo-testing、elrepo-kernel，默认只有第一个是开启的，其余三个都是关闭的
elrepo，主要模块并且默认开启。由于没有默认放在Linux系统的发行包中，所以执行yum update不会出现问题。
elrepo-extra，用于更新Linux系统发行包的替代或更新包
elrepo-testing，提供给elrepo的一些相关联的包
elrepo-kernel，包含longlong-term和mainline版本的Linux核心包，根据Linux官网发布的内核包产生的
(•̀ᴗ•́)و ̑̑