Re: Re: Re: faster boots?

Re: Re: Re: faster boots?

[joeja]

Someone pointed out that I may have to much stuff built into the kernel and that I should try modularizing it.  Only builing in what I need to boot and the rest as modules. 

This may be true.

It is easier IMHO to configure a NetBSD kernel or FreeBSD kernel with just what you need in the system because dmesg is more helpful IHMO on those systems.

dmesg for netbsd prints stuff like

pckbc0: using irq 12 for aux slot

and in its kernel config file there will be a line something like

pckbc* irq* 

or something.  Thus someone wrote a nifty little perl script that can go through dmesg and comment out of the config what is not found by the generic kernel (or the kernel installed at that time).  This helped reduce my netbsd kernel from 3.6M to about 2.1M and speed up the machine some.

FreeBSD is very similar to this.  Only I think it tends to have more modules in the default generic kernel.

Linux on the other hand prints out all this other stuff which makes it harder IMHO to determine weather or not you need driver foo built into the kernel.  Thus I know that when I build a Linux kernel there is stuff that is in it that I don't need but don't know what it is.

Also the bsd's run 'config' against the config file which actually checks to see if the config file that was edited is actually going to build and it also updates some other stuff.  Although that is not 100% accurate, but a big help.

So what is the best way in Linux to figure out what you can remove from the kernel to make it smaller and boot hopefully faster on low end machines?

Joe

Re: Re: Re: faster boots?

[Alan Cox]

> So what is the best way in Linux to figure out what you can remove from the 
> kernel to make it smaller and boot hopefully faster on low end machines?

Say "M" to everything that isnt your root file system or directly dependant
on it. The whole "build a custom kernel" thing is mostly a red herring.

Re: Re: Re: faster boots?

[Mr. James W. Laferriere]

	Hello Alan ,  ONLY in YOUR opinion .  Not mine '.' .  JimL

On Sat, 6 Apr 2002, Alan Cox wrote:

> > So what is the best way in Linux to figure out what you can remove from the
> > kernel to make it smaller and boot hopefully faster on low end machines?
>
> Say "M" to everything that isnt your root file system or directly dependant
> on it. The whole "build a custom kernel" thing is mostly a red herring.
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Re: faster boots?

[Joe]

Thanks all,
    several people had suggested this.

    as it turns out one thing that was slowing my boot down was actually the
framebuffer.  When the kernel boots and it switches to mode 0x317 (maybe other
modes or all did not try) it would actually take a second or two to switch to
the new mode.  This is on a fast machine so I imagine that on a slower machine
it may take longer.

    also it seems that ide2 probe would take long as well.  maybe less than 1/2
second but it would be noticable so adding ide2=noprobe helped as well.  this
may be that there is no ide2 and it has to time out.  I guess the time out is
very small.

    also the cdrom probe takes a little time as well...

    removeing all these unnecessary drivers has speed it up some more as well.
it seems it now boots in about 1/2 the time.

Joe

> > So what is the best way in Linux to figure out what you can remove from the
> > kernel to make it smaller and boot hopefully faster on low end machines?
>
> Say "M" to everything that isnt your root file system or directly dependant
> on it. The whole "build a custom kernel" thing is mostly a red herring.