Use a HIGHMEM enabled kernel.

[Harstad]

Hi

I´ve added 2GB of memory to the system.
Seeing the messages file appears the following alarms:

Warning only 896MB will be used.
Apr 19 17:50:27 mas-preprod kernel: Use a HIGHMEM enabled kernel.
Apr 19 17:50:27 mas-preprod kernel: 896MB LOWMEM available.

Could you please inform how can I enable the HIGHMEM option?'

Thanks

Harsta

[Mark Grant]

This will depend on your distribution but basically you need to compile a kernel with the HIGHMEM configuration option set. The actual option is CONFIG_HIGHMEM4G. PLease see your distributions documentation for compiling your own kernel.

[Harstad]

Hi

Actually,,the system has just 1GB,,

How can I see the default value for the HIGHMEM??

thanks

Harstad

[Mark Grant]

If you mean what is it now, then go to your kernel source directory, generally speaking this is "/usr/src/linux" and go "grep HIGHMEM .config".

When you set the option, you have to say what to set it to and the default is 4GB. It is quite important that you don't specify 64GB here if your CPU(s) can't support the intel PAE as the machine won't boot.

[Harstad]

Hi

The actual kernel version is: 2.4.18-10

[Roberto Polli]

Ok, first of all:
1) which distro do you use?
2) did you build your kernel from scratch or it's a default one?

If you have a kernel taken from rpm (eg. use a Redhat linux) to check the bigmem flag you should only grep the file /usr/src/linux/configs/kernel*.config
which matche more with the output of
uname -sm

as suggested in one of the message above.

From the same distro you should only unpack the new kernel named kernel-......-bigmem...rpm ancd check lilo or grub to boot using it.

Else read the kernel HOWTO and compile it, even if compiling 'RH customized ' kernel gave me some problems.

Pax, R.

[Martin P.J. Zinser]

Hi,

and if you do have build your own kernel the config file should be /usr/src/linux/.config

If you want to build your own kernel follow the instructions in the README file of the source directory.

Greetings, Martin

[dirk dierickx]

If you are using RH you will notice there are different kernel packages delivered.
in your case you need the 'bigmem' package, after installation it should be available from the boot menu, check if it works ok, and then you can put it as your default boot kernel.