mirror of
https://github.com/torvalds/linux.git
synced 2024-11-08 13:11:45 +00:00
f5c24a7fd0
Intel recommends to not use large pages for the first 1MB of the physical memory because there are fixed size MTRRs there which cause splitups in the TLBs. On AMD doing so is also a good idea. The implementation is a little different between 32bit and 64bit. On 32bit I just taught the initial page table set up about this because it was very simple to do. This also has the advantage that the risk of a prefetch ever seeing the page even if it only exists for a short time is minimized. On 64bit that is not quite possible, so use set_memory_4k() a little later (in check_bugs) instead. Signed-off-by: Andi Kleen <ak@suse.de> Acked-by: andreas.herrmann3@amd.com Cc: mingo@elte.hu Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
34 lines
778 B
C
34 lines
778 B
C
/*
|
|
* Copyright (C) 1994 Linus Torvalds
|
|
* Copyright (C) 2000 SuSE
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <asm/alternative.h>
|
|
#include <asm/bugs.h>
|
|
#include <asm/processor.h>
|
|
#include <asm/mtrr.h>
|
|
#include <asm/cacheflush.h>
|
|
|
|
void __init check_bugs(void)
|
|
{
|
|
identify_boot_cpu();
|
|
#if !defined(CONFIG_SMP)
|
|
printk("CPU: ");
|
|
print_cpu_info(&boot_cpu_data);
|
|
#endif
|
|
alternative_instructions();
|
|
|
|
/*
|
|
* Make sure the first 2MB area is not mapped by huge pages
|
|
* There are typically fixed size MTRRs in there and overlapping
|
|
* MTRRs into large pages causes slow downs.
|
|
*
|
|
* Right now we don't do that with gbpages because there seems
|
|
* very little benefit for that case.
|
|
*/
|
|
if (!direct_gbpages)
|
|
set_memory_4k((unsigned long)__va(0), 1);
|
|
}
|