Auto Detection of RAM Larger than 1GB

**Mycroft1855** · 03-04-2003, 11:08 PM

I know that when installing most distros of linux you need to specify the amount of memory if it is larger than 1gb. Is there anyway to have knoppix autodetect the amount of memory over 1gb? Also if it isn't possible how do you change the known memory setting in knoppix.

Thanks.

**rickenbacherus** · 03-07-2003, 11:55 PM

Pass this to the kernel:

mem=xxxM

replace 'xxx' with your amout of memory (in megabytes not gigabytes) and be sure to use a capital M.

e.g. if you have 512 MB ram then type this on the command line:

knoppix mem=512M

**tuxtom** · 03-09-2003, 02:40 PM

The kernel used by knoppix supports only ~ 900 MB of RAM.
For more you should build a kernel w/ the following settings in /usr/src/linux/.config

Code:

CONFIG_NOHIGHMEM=n
CONFIG_HIGHMEM4G=y
# CONFIG_HIGHMEM64G is not set
CONFIG_HIGHMEM=y

tom

**rickenbacherus** · 03-10-2003, 03:24 AM

Only 900 MB huh? I wonder what it's like to have that much freaking RAM....................?

**Mycroft1855** · 03-10-2003, 03:45 AM

900mb...i'm working on something that needs to work with up to 16gb of ram and 2gb on a regular basis. Always fun stuff.

**David Douthitt** · 03-12-2003, 03:40 AM

Originally Posted by tuxtom

The kernel used by knoppix supports only ~ 900 MB of RAM.
For more you should build a kernel w/ the following settings in /usr/src/linux/.config

Code:

CONFIG_NOHIGHMEM=n
CONFIG_HIGHMEM4G=y
# CONFIG_HIGHMEM64G is not set
CONFIG_HIGHMEM=y

tom

Can you compile a new kernel with new settings and put it onto a Knoppix boot floppy to startup the CDROM?

Knoppix also doesn't have CONFIG_SCSI_MULTI_LUN set - which means that multi-card readers for USB don't work...

**santakaos** · 03-20-2003, 10:58 PM

Well, I think I had undertood your question: more than 1GB RAM in the autodetection.

The autodetection in Knoppix is made by miniroot.gz file, which is inside the boot.img. When you mount the boot image , you can:

Code:

gzip -d miniroot.gz

then mount miniroot file:

Code:

 mount -t msdos -o loop miniroot /mountpoint

. Look inside. There is a file called 'linuxvrc' that has ALL the autodetection code. At the beginning of the script someone thought that 1GB would be enough RAM memory to search. you can change the variable here as you want. (the code is quite good commented).
I dont know much about kernels, but I'm totally sure that if you don't touch this you will never make your RAM work.

(Sorry for my english, i hope you understand me)

SANTA
(Guadalajara, Spain)