hi folks,

currently i'm using kernel-version 2.4.18 which is included in SuSE professional 8.0
when i first configure it before compiling and stuff using menuconfig, it has the option "High Memory Support" enabled with a setting to 4GB. well, the question to me is if it should be disabled if i don't have more than 960 Meg installed.
i haven't compared both "off" and "4GB" to well yet but does support for "high memory" slow down a machine that has less?

thx in advance!

It shouldn't be slower, but I don't know why you would like --> 4GB RAM support if you have only 960MB....
[addsig]

well, i don't exactly want -->4GB support. it's just that i wanted to know if it may be good to disable it if not needed, you know?

always disable what you don't need. It will just eat RAM if you build it into the kernel and never need it. That's the whole point of "configuring" the kernel Throw out stuff you don't need, but build stuff you do need.
On todays computers you won't feel a difference tho. Only on those very old thingies, where you have very limited RAM. But, if you would like to create a bootdisk with that kernel, take _everything_ out you don't need, or you won't get it fit on the floppy...
[addsig]

What I usually do when compiling a fresh kernel for a new machine is un-check everything, then carefully go through all the menus and select only what I'm sure I'll need, always using modules, if possible.

That way you have a minimal kernel that won't carry useless ballast.

So when you get a new kernel version, you just copy the .config from the old source dir to the new one, and recompile.

By the way, you can easily add new things to the kernel without rebooting (if it's available as a module) by just doing a make modules modules_install and loading the module.

i know, that's what i do usually or - to put in another way - used to do. since kernel version 2.4 and higher SuSE messed with the kernel sources in some way which caused a major problem: when one tries to recompile modules and install them afterwards system happens to don't know the right names of the modules anymore. this annoys me far too much so i usually just remove things or add in-compiled 'modules' since the standard kernel seems to be compiled in a quite sufficient way. YES, i'm lazy as hell but who cares anyway? ^.^* [addsig]

and, I think the .config file won't apply to new options added to the kernel between 2 different versions. So if you get a new version, copy the .config file over, you will maybe have some "unwanted sideeffects"
Anyways, there _are_ some things which won't work properly if you don't compile/use them as modules. For example if you have 4ps speakers with a sub, you will always need to compile/use the sound driver as a module or the rear speakers will be dead silent.
My Kernel-Habits are something like:
compile into the kernel what you definitely need all the time (SCSI emulation, USB mass-storage - Accessing the MemoryStick of my pilot; USB full input support - my USB mouse; various file-systems; usb--->serial - for syncing my pilot etc.), and as modules what you use occassinally, or what does only work properly as a module, like the sound card stuff I mentioned above.

But back to the 4GB RAM thingy:
What do you actually need it for?
[addsig]

copying .config over is no problem at all, i do it all the time, never had anything bad happen (:

you can even copy a .config from a more recent kernel to an older kernel, even if there's stuff selected in there that the older one doesn't have yet. they just get stripped.

cool, maybe I should try that too
But, I also like re-configuring it from time to time, because I can discover the new features each time
[addsig]

as i said before, i wonder if the bigger adress-space the 4gb option is using when being enabled somehow slows down things or not. what actually is done by the kernel to adress that much of memory i don't really know. well, i could imaginge that a simple adress is not 32bit but 64bit for 4gb support or whatever. i'm not very into that kind of things...

I would say that you won't notice any speed changes on today's PCs. Tho, I haven't tried it
[addsig]

oh well, it's not that it's an critical issue or seomthing. just wondered, thx guys!

if we really helped you:
no problem! you're welcome
[addsig]