Hi, guys,

I need some help on activating an 128 KB L2 cache on a Celeron A processor. The processor is part of a Powerleap Pro/II cpu upgrade pkg. Unfortunately on power up the cache is disabled (32kb L1 only). This was true when I was running Win98, and is still true now, as shown by executing "leafpad \proc\cpuinfo" in my new Zenwalk install. However, in Win98, Powerleap provided a program to enable the L2cache and I had it run on Win98 startup. But no sucg program exists for Linux, at least not from Powerleap directly.

However, a patch has been written to perform the L2 cache enabling in Linux. It works with version 2.2 kernel and was written by Peter Schneider 01/21/00.

Here is the code:


L2enabler_v1.txt version 1.0

#define MODULE
#define __KERNEL__
#include <linux/module.h>

#include <asm/system.h> /* cli(), *_flags */


static inline void disable_cache(void)
{
asm volatile (
"movl %%cr0, %%eax\n\t"
"orl $0x40000000, %%eax\n\t"
"movl %%eax, %%cr0\n\t"
:
:
:"memory", "cc", "eax");
}

/* ... */
static inline void enable_cache(void)
{
asm volatile (
"movl %%cr0, %%eax\n\t"
"andl $0xbfffffff, %%eax\n\t"
"movl %%eax, %%cr0"
:
:
:"memory", "cc", "eax");
}


int init_module(void)
{
unsigned long flags;
printk ("<1>L2Enabler: Will enable L2 cache on a Celeron\n");

save_flags(flags);
cli ();
//Disable L1 Cache
__asm__ ("wbinvd");
disable_cache ();
__asm__ ("wbinvd");
//Read L2 Cache MSR
__asm__ ("mov $0x11E, %ecx");
__asm__ ("rdmsr");
//Enable it
__asm__ ("or $0x00040101, %eax");
//Write to L2 Cache MSR
__asm__ ("mov $0x11E, %ecx");
__asm__ ("wrmsr");
//Enable L1 Cache
__asm__ ("wbinvd");
enable_cache();
__asm__ ("wbinvd");
//__asm__ ("invd");
restore_flags(flags);
printk ("<1>Done enabling L2 cache\n");

return 0;
}

void cleanup_module (void)
{
printk ("<1>Goodbye from the L2Enabler\n");
}


What I need to know is whather this is still valid for the current kernel version, and, if so, how would the "patching" be done?

Thanks for any help you might be able to provide.

Steve

the cache enable/disable setting is usually found in the BIOS settings of a computer.
most computers give some message when first turned on like "press F1 to enter setup" or "press delete for CMOS"

but then again some computers have "pretty" boot up screens that hide all that stuff. If you don't have the manual to look up such a thing then try restarting your computer and pressing as many different keys starting with delete and go up the F# keys.

once inside your BIOS settings be careful not change important things like harddrive LZ and WPC. just look for your L2 cache setting.

if its something other than that i'm sorry cause im no help.

Thanks but the BIOS is quite old (I am using a Dell Optiplex GXPro, ca 1998). There is no option to control much of anything of importance to any great degree. The CPU I want enabled is a "powerleap upgrade Celeron A" running @ 533MHZ, whereas the original CPU was a Pentium Pro @ 200MHZ.

I need to run some auxiliary program or have some auxiliary code executed in order to activate the L2 cache on the CPU. Otherwise it works at an effective speed of 300MHZ.

Thanks for your help

Steve