Henning Brauer takes up the cudgels for kernel cUst0mIz0rz =)

[mish]

From misc@, 060708:

Date: Sat, 7 Jun 2008 19:39:42 +0200
From: Henning Brauer <lists-openbsd@bsws.de>
To: misc@openbsd.org
Subject: Re: "remove any unwanted devices from the kernel. "
Message-ID: <20080607173942.GB7628@nudo.bsws.de>

* Jon <jonforthewin@gmail.com> [2008-06-06 03:04]:
> Why would someone want to do this?

because it is plain boring to just use GENERIC.

fiddling with your kernel, you can waste a lot of time to get it to
compile, then brag about that over beer with your friends, and while
they keep drinking your pager alerts you back because your kernel
crashed, since you also like to play with compiler "optimization"
levels. While you are allowed to play more iwth your kernel, your
friends just sit somewhere and drink, what a choice.
After a while you don't have friends any more, but a custom kernel that
boots 3 seconds faster than GENERIC and is stable for some time.
Certainly worth it.

--
Henning Brauer, hb@bsws.de, henning@openbsd.org
BS Web Services, http://bsws.de
Full-Service ISP - Secure Hosting, Mail and DNS Services
Dedicated Servers, Rootservers, Application Hosting - Hamburg & Amsterdam

[BSDfan666]

I'll never understand why people insist on tinkering with their kernel... it's like a person rewiring their new cars electrical system an hour after purchasing it.

If you want a slightly faster boot time, use instead config(8), Any performance gains from customizing GENERIC will be *very* negligible.

Also, don't mess with the CFLAGS, while it's common practise for Linux users to add "optimizations", they're unnecessary and often *dangerous* when messed with.

[unicyclist]

Originally Posted by BSDfan666

I'll never understand why people insist on tinkering with their kernel... it's like a person rewiring their new cars electrical system an hour after purchasing it.

If you want a slightly faster boot time, use instead config(8), Any performance gains from customizing GENERIC will be *very* negligible.

Also, don't mess with the CFLAGS, while it's common practise for Linux users to add "optimizations", they're unnecessary and often *dangerous* when messed with.

It might depend on their background as to why some rebuild their kernel.
Some, like myself, may have come from FreeBSD (early releases) where the first thing you did was rebuild your kernel to enable/disable items you needed. IIRC, even pcm was disabled in GENERIC kernel. I would have to double-check my 3.x, 4.x cd's to verify, but the basic GENERIC kernel was very basic
I think the OpenBSD kernel would be similar to the older FreeBSD LINT kernel (hope I got the name right). A person copied needed items from that to a new kernel and rebuilt it.
Perhaps that's why some want to tinker. I had to build quite a few linux kernels in the earlier days so that even nowadays, the habit is strong enough to think of before I realize that I'm using OpenBSD and all I need to do is use "config -ef /bsd" to get what I want/need

Perhaps on the faq webpage, for the link to customizing a kernel, there should be a link to a page that just says "NO, DON'T, use config instead" and leave it at that

[ohauer]

I can agree with Henning but i remember also an (for me) interesting thread that solves my problem with soekris and hifn (read the complete thread).
http://readlist.com/lists/openbsd.or.../12/61303.html

If i remember the card worked for me with 3.7/3.8, some trouble with 3.9 but was broken in 4.0/4,1 and the standart answer was 'it is the buggy hifn chip'

[ocicat]

Originally Posted by unicyclist

Some, like myself, may have come from FreeBSD (early releases) where the first thing you did was rebuild your kernel to enable/disable items you needed.

Although I understand your comparison, you are also contrasting FreeBSD when it was in its infancy, & there are significant differences between the project cultures today. You know, the whole apples & oranges thing...

The fact that there are non-BSD projects which promote compile happy mantras declaring "Compiler option tweaking is as good as flossing!" does everyone a disservice. The truth is that responsible tweaking requires understanding the ramifications of the decisions made, & this only comes from significant experience with studying the code. As has been stated in the same thread on misc@, shaving drivers doesn't really reduce the kernel's size by appreciable amounts.

Even tools like dmassage aren't that useful today as it only hunts through the output of dmesg(8) for "not configured" driver messages.

So the point on misc@ is that the developers are very jaded about efforts attempting to run the kernel in 1k as they have seen people dig themselves into very deep holes. While the code is available for anyone to do anything, just don't come crying when it has been broken.

[roundkat]

I have watched /read Hennings' rants over the years..

He is like a Theo "light"

[cursedcompiler]

usually it's best to stick with a generic kernel and default userland, but personally i always tweak little things here and there... i'd even say it is desirable in some situations (eg., low memory or slow and little boot media)