RAM upgrade - HIGH MEMORY SUPPORT on Debian

simonm · Post by **simonm** » Thu Aug 10, 2006 2:20 pm

Hello,
I have upgraded my ZM server from 512 MB to 2 GB of RAM.
But Debian only recognizes 880 MB.
As I read, It's a kernel related problem - I have to compile a kernel with High Memory Support.

But now I found in /boot/config-2.6.8-3-386 this section:

Code: Select all

#
# Firmware Drivers
#
CONFIG_EDD=m
CONFIG_NOHIGHMEM=y
# CONFIG_HIGHMEM4G is not set
# CONFIG_HIGHMEM64G is not set
CONFIG_MATH_EMULATION=y
CONFIG_MTRR=y
# CONFIG_EFI is not set
# CONFIG_REGPARM is not set

Can anybody give a kernel-compile-afraid admin some hints how to solve the problem, so that 2 GB of RAM a recognized?

Thanks!

Simon

jameswilson · Post by **jameswilson** » Thu Aug 10, 2006 2:29 pm

you will have to recompile with himem suppoer you cant just turn it on. Or add a kernel that has himem support, this is possible on the mandrake stuff but not sure on debian

Flash_ · Post by **Flash_** » Fri Aug 11, 2006 6:14 am

Yep - it's the same for Debian.

Easiest way is to use apt-get to install a new kernel that has HIMEM support enabled.

simonm · Post by **simonm** » Fri Aug 11, 2006 6:20 am

Hello Flash,
is highmem support in all newer kernel versions enabled (if so, i would simply choose the newest kernel) or where can I find out which kernel supports highmem?

Thanks!!
Simon

jameswilson · Post by **jameswilson** » Fri Aug 11, 2006 7:57 am

no will have to find a kenrel with highmem support. There are loads of differentr options for the kernel and hig/low mem support is nothing to do with the kernel version mate

simonm · Post by **simonm** » Fri Aug 11, 2006 8:03 am

Ok, thanks!

Regards,
Simon

Post by **Flasheart** » Fri Aug 11, 2006 12:36 pm

Yep - for some reason it's not usually enabled by default. For my last server I had to build a specific kernel for it (also as it's a quad cpu machine, SMB needs to be enabled too).

That said, building a kernel under debian is quite easy if you build it as a .deb package which you can then install. A basic howto is below. and there are hundreds of other guides on building a kernel.

http://www.debian-administration.org/articles/90

simonm · Post by **simonm** » Fri Aug 11, 2006 2:40 pm

Wow, thanks. I'll give it a try.

But before i will do a veeeery good image....

Flash_ · Post by **Flash_** » Sat Aug 12, 2006 9:00 am

Backups are always good.

But if you;'re using Grub or Lilo as boot manager, it's very easy to set so that it gives you a menu of which kernel you want it to run at boot-time. As you're experimenting, best to set that so that it defaults to loading your existing kernel, unless you tell it different on boot (times out after 10 seconds or so and loads the default). That way you can play and be reasonably sure you're not going to be unable to access your pc if the new kernel breaks.