How do I enable the kernel for HIGHMEM?
 

I just installed a gig of DDR RAM on Mandrake 10 2.4.25-2mdk. Windows and BIOS both see 1024MB but Mandrake only sees 896MB.

I edited lilo.conf to add "mem=1024M" and that didn't help. I ran dmesg and see an error message saying I need a HIGHMEM enabled kernel in order to use the rest of the RAM.

So..... umm........... I do that how?



[mike@localhost mike]$ dmesg
Linux version 2.4.25-2mdk (nplanel@no.mandrakesoft.com) (gcc version 3.3.2 (Mand
rake Linux 10.0 3.3.2-6mdk)) #1 Tue Mar 2 07:39:08 CET 2004
BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 000000003fff0000 (usable)
BIOS-e820: 000000003fff0000 - 000000003fff8000 (ACPI data)
BIOS-e820: 000000003fff8000 - 0000000040000000 (ACPI NVS)
BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
BIOS-e820: 00000000ffee0000 - 00000000fff00000 (reserved)
BIOS-e820: 00000000fffc0000 - 0000000100000000 (reserved)
user-defined physical RAM map:
user: 0000000000000000 - 000000000009fc00 (usable)
user: 000000000009fc00 - 00000000000a0000 (reserved)
user: 00000000000f0000 - 0000000000100000 (reserved)
user: 0000000000100000 - 000000003fff0000 (usable)
user: 000000003fff0000 - 000000003fff8000 (ACPI data)
user: 000000003fff8000 - 0000000040000000 (ACPI NVS)
user: 00000000fec00000 - 00000000fec01000 (reserved)
user: 00000000fee00000 - 00000000fee01000 (reserved)
user: 00000000ffee0000 - 00000000fff00000 (reserved)
user: 00000000fffc0000 - 0000000100000000 (reserved)
Warning only 896MB will be used.
Use a HIGHMEM enabled kernel.
896MB LOWMEM available.

You compile yourself a new kernel and this time turn on the appropriately labled "HIGHMEMORY SUPPORT"

That's about it?

If you cant find enough posts here explaining how to compile a kernel then your in need of serious help.

No you don't have to recompile a new kernel. Use the software installer look for the kernel that supports 1 gig of memory or more. Such as kernel-i686-up-4GB-2.4.25.2mdk. If this doesn't work you can add an option to your lilo.conf file to specify the exact am out of memory(The system Ive built with one gig of mem didn't need this option just the new kernel). If it Mandrake you don't have to recompile the kernel every time you want to change hardware.

Oh cool. Thanks. I see it in the installer now.

I was running around looking for "How-To"s to recompile. I've only switched from Windows to Linux for about a week, so "recompiling your kernel" sounds like some sort of witchcraft.

Recompiling a kernel isn't that bad but Ive only had to recompile a kernel once in 4 yrs and that was 2yrs ago.

That did it. Installed it and rebooted and it detected most of it. It sees 1008MB instead of 1024, but I'm not gonna argue with it about 16MB.