[elrepo] How to understand elrepo kernel config changes

[Chengwei Yang]

Hi Phil,

I found a problem here.

I'm testing kernel-lt 4.4.186-1 on a 2socket skylake server with X722 rev09 ethernet network connection.

I fount that the i40e driver version is 1.3.46-k which doesn't support X722
device while centos 7.4's latest kernel 3.10.0-693.21.1 does.

Because I'm new to kernel and now I'm worrying there are some other traps like
this to use kernel-lt.

On Mon, Aug/05/2019 at 09:51:09 +0800, Chengwei Yang wrote:
> On Fri, Aug/02/2019 at 20:50:12 +0100, Phil Perry wrote:
> > On 02/08/2019 07:58, Chengwei Yang wrote:
> > > 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.
> > > 
> > 
> > I guess I should explain the history of how we ended up where we are today
> > with the config file.
> > 
> > The config file started it's life around the time of kernel-3.14. The
> > current RHEL el7 kernel config was taken as a starting point and all new
> > options were reviewed and set on a case by case basis to generate an initial
> > release candidate. A lot of testing and further release candidates followed
> > and ultimately culminated in the release of a 3.15.0 kernel as the first el7
> > 'GA' release.
> > 
> > For every subsequent new source code release, any new configuration options
> > were again considered on a case by case basis. If the new option was part of
> > a pre-existing option that was already enabled, then the new option would
> > generally be enabled also.
> > 
> > Along the way many users have requested options be enabled within the
> > kernel. These requests have generally been actioned unless deemed to be
> > detrimental or otherwise not advisable. (Such requests should be made as
> > RFEs's against the appropriate kernel package on elrepo.org/bugs otherwise
> > they will be ignored).
> > 
> > The above process originally started out it's life as kernel-ml and then
> > back in March 2016 forked to become kernel-lt with the release of
> > kernel-lt-4.4.6.
> > 
> > The above process has been meticulously documented within the package
> > changelog, which you can inspect in the (S)RPM or here:
> > 
> > https://github.com/elrepo/packages/blob/master/kernel-lt/el7/kernel-lt-4.4.spec
> > 
> > To understand the changes, you will need to individually review each in
> > turn, reading the documentation for each as Alan has done over the last 5+
> > years when making those decisions.
> > 
> > Hope that helps.
> 
> Thank Phil for your great patients, it did answered my question and the
> changelog is helpful.
> 
> > 
> > Phil
> > 
> > _______________________________________________
> > elrepo mailing list
> > elrepo at lists.elrepo.org
> > http://lists.elrepo.org/mailman/listinfo/elrepo
> 
> -- 
> Thanks,
> Chengwei

-- 
Thanks,
Chengwei