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Subject2.5.62 ioremap fails
I have been trying to allocate memory past the end of the kernel in a system
that has more that 1 Gb of memory and have been unsuccessful. My current
machine has an athlon processor and 1.5Gb of memory.

I created a driver with the following code:

#define MAXHM 0x8000000 // 128 Mb
int __init init_module(void)
void *kHighMem;

printk(KERN_ERR"before ioremap\n");
kHighMem = ioremap(__pa(high_memory), MAXHM);
printk(KERN_ERR"ioremap ret: %x\n",kHighMem);

return 0;

void __exit leave_mod(void) {
printk(KERN_ERR"iounmap passed\n");

printk(KERN_ERR,"module successfully unloaded.\n");

I add the line append="mem=xx" to lilo.
If I set "xx" to around 860 or above then ioremap fails. If I set "xx" to
860 or less then ioremap is successful. Has anyone had any experience
trying to allocate a contiguous memory buffer beyond the end of what the
kernel manages in a system with over 1Gb of memory? Any help would be
appreciated in this matter.

Rob Murphy

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