Re: Memory trouble
On Fri, 2006-03-24 at 13:28 -0500, Yu,Glen [Ontario] wrote:
> Hi everyone,
>
> This is kind of long, so bear with me...
>
> I have used Linux (FC, SuSE, and recently Debian 3.1) for many years in the past, but have never actually done and modification/configuration of the kernel, and would like some pointers/tips or maybe a useful link to a guide which give good instructions as to how to configure the kernel (specifically for Debian 3.1). I see a few tutorials when I google this topic, but none are specific to Debian (example: they tell you to go to /usr/src/linux, but I don't have that directory =| ).
>
> What I'm trying to do is this:
> At work, we've recently installed a new Dell PowerEdge 2800 server with 2 (single-core) 3.6GHz Xeon CPUs w/2MB L2 cache, 8GB of memory, and a few TB of HDD space. We've installed the 2.4.27-2-686-smp kernet and it works fine except for 2 thing:
>
> 1) cat /proc/meminfo (and free) shows that it only sees 4GB of memory
> 2) cat /proc/cpuinfo and dmesg shows only the L1 cache (16K) and L2 cache seems to have disappeared into thin air =(
>
> I believe the solution to problem #1 is to modifiy the kernel settings and set CONFIG_HIGHMEM64G=y (at the moment CONFIG_HIGHMEM4G=y, and the 64G one is commented out), but I can't just edit the /boot/config-2.4.27-2-686-smp file directly, hence I need a tutorial on kernel config.
>
> As for problem #2, I have yet to find any clue whatsoever as to why it's happening and how I can fix the problem, so if anybody can provide any sort of insight to this, I would very much appreciate it.
the reason nothing is in /usr/src/linux is because you dont have the
source to the kernel (or you do, and it just isnt in /usr/src/). the
location of the kernel source tree is not that important.
so install the source, and some other tools to make a debian kernel
package:
# aptitude install kernel-source-2.4.27 fakeroot kernel-package
libncurses5-dev
let a normal user do stuff under /usr/src
# adduser glen src
logout, login
glen$ tar xfj /usr/src/kernel-source.2.4.27*.tar.bz2
get the config file for your current running kernel
tweak this tweak this
vvvvvvvvvvvvv vvvvvvvvvvvvvvvvvvvv
glen$ cp /boot/config-2.4.27 /usr/src/kernel-source-2.4.27/.config
glen$ cd /usr/src/kernel-source-2.4.27/ && make oldconfig
glen$ make menuconfig
find the high mem option, it should be under the processor options
glen$ fakeroot make-kpkg clean
glen$ fakeroot make-kpkg --append-to-version=$(date +%Y%m%d.%H%M)
--initrd kernel_image
tweak this
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
# dpkg -i /usr/src/kernel-image-2.4.27<whatever>.deb
reboot!
(i may have forgotten a step or two, :) but if you keep your old kernel
around you should always be able to boot into that.
-matt zagrabelny
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