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Commit 093af8d7 authored by Yinghai Lu's avatar Yinghai Lu Committed by Ingo Molnar
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x86_32: trim memory by updating e820 



when MTRRs are not covering the whole e820 table, we need to trim the
RAM and need to update e820.

reuse some code on 64-bit as well.

here need to add early_get_cap and use it in early_cpu_detect, and move
mtrr_bp_init early.

The code successfully trimmed the memory map on Justin's system:

from:

 [    0.000000]  BIOS-e820: 0000000100000000 - 000000022c000000 (usable)

to:

 [    0.000000]   modified: 0000000100000000 - 0000000228000000 (usable)
 [    0.000000]   modified: 0000000228000000 - 000000022c000000 (reserved)

According to Justin it makes quite a difference:

|  When I boot the box without any trimming it acts like a 286 or 386,
|  takes about 10 minutes to boot (using raptor disks).

Signed-off-by: default avatarYinghai Lu <yinghai.lu@sun.com>
Tested-by: default avatarJustin Piszcz <jpiszcz@lucidpixels.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 11201e60

Documentation/kernel-parameters.txt

+1 −1
Original line number Diff line number Diff line
@@ -583,7 +583,7 @@ and is between 256 and 4096 characters. It is defined in the file 
			See drivers/char/README.epca and

			Documentation/digiepca.txt.



	disable_mtrr_trim [X86-64, Intel only]

	disable_mtrr_trim [X86, Intel and AMD only]

			By default the kernel will trim any uncacheable

			memory out of your available memory pool based on

			MTRR settings.  This parameter disables that behavior,

arch/x86/kernel/cpu/common.c

+29 −1
Original line number Diff line number Diff line
@@ -278,6 +278,33 @@ void __init cpu_detect(struct cpuinfo_x86 *c) 
			c->x86_cache_alignment = ((misc >> 8) & 0xff) * 8;

	}

}

static void __cpuinit early_get_cap(struct cpuinfo_x86 *c)

{

	u32 tfms, xlvl;

	int ebx;



	memset(&c->x86_capability, 0, sizeof c->x86_capability);

	if (have_cpuid_p()) {

		/* Intel-defined flags: level 0x00000001 */

		if (c->cpuid_level >= 0x00000001) {

			u32 capability, excap;

			cpuid(0x00000001, &tfms, &ebx, &excap, &capability);

			c->x86_capability[0] = capability;

			c->x86_capability[4] = excap;

		}



		/* AMD-defined flags: level 0x80000001 */

		xlvl = cpuid_eax(0x80000000);

		if ((xlvl & 0xffff0000) == 0x80000000) {

			if (xlvl >= 0x80000001) {

				c->x86_capability[1] = cpuid_edx(0x80000001);

				c->x86_capability[6] = cpuid_ecx(0x80000001);

			}

		}



	}



}



/* Do minimum CPU detection early.

   Fields really needed: vendor, cpuid_level, family, model, mask, cache alignment.
@@ -306,6 +333,8 @@ static void __init early_cpu_detect(void) 
		early_init_intel(c);

		break;

	}



	early_get_cap(c);

}



static void __cpuinit generic_identify(struct cpuinfo_x86 * c)
@@ -485,7 +514,6 @@ void __init identify_boot_cpu(void) 
	identify_cpu(&boot_cpu_data);

	sysenter_setup();

	enable_sep_cpu();

	mtrr_bp_init();

}



void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)

arch/x86/kernel/cpu/mtrr/main.c

+14 −8
Original line number Diff line number Diff line
@@ -624,7 +624,6 @@ static struct sysdev_driver mtrr_sysdev_driver = { 
	.resume		= mtrr_restore,

};



#ifdef CONFIG_X86_64

static int disable_mtrr_trim;



static int __init disable_mtrr_trim_setup(char *str)
@@ -643,13 +642,10 @@ early_param("disable_mtrr_trim", disable_mtrr_trim_setup); 
#define Tom2Enabled (1U << 21)

#define Tom2ForceMemTypeWB (1U << 22)



static __init int amd_special_default_mtrr(unsigned long end_pfn)

static __init int amd_special_default_mtrr(void)

{

	u32 l, h;



	/* Doesn't apply to memory < 4GB */

	if (end_pfn <= (0xffffffff >> PAGE_SHIFT))

		return 0;

	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)

		return 0;

	if (boot_cpu_data.x86 < 0xf || boot_cpu_data.x86 > 0x11)
@@ -687,9 +683,14 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) 
	 * Make sure we only trim uncachable memory on machines that

	 * support the Intel MTRR architecture:

	 */

	if (!is_cpu(INTEL) || disable_mtrr_trim)

		return 0;

	rdmsr(MTRRdefType_MSR, def, dummy);

	def &= 0xff;

	if (!is_cpu(INTEL) || disable_mtrr_trim || def != MTRR_TYPE_UNCACHABLE)

	if (def != MTRR_TYPE_UNCACHABLE)

		return 0;



	if (amd_special_default_mtrr())

		return 0;



	/* Find highest cached pfn */
@@ -703,8 +704,14 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) 
			highest_addr = base + size;

	}



	if (amd_special_default_mtrr(end_pfn))

	/* kvm/qemu doesn't have mtrr set right, don't trim them all */

	if (!highest_addr) {

		printk(KERN_WARNING "***************\n");

		printk(KERN_WARNING "**** WARNING: likely strange cpu\n");

		printk(KERN_WARNING "**** MTRRs all blank, cpu in qemu?\n");

		printk(KERN_WARNING "***************\n");

		return 0;

	}



	if ((highest_addr >> PAGE_SHIFT) < end_pfn) {

		printk(KERN_WARNING "***************\n");
@@ -726,7 +733,6 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) 


	return 0;

}

#endif



/**

 * mtrr_bp_init - initialize mtrrs on the boot CPU

arch/x86/kernel/e820_32.c

+11 −0
Original line number Diff line number Diff line
@@ -749,3 +749,14 @@ static int __init parse_memmap(char *arg) 
	return 0;

}

early_param("memmap", parse_memmap);

void __init update_e820(void)

{

	u8 nr_map;



	nr_map = e820.nr_map;

	if (sanitize_e820_map(e820.map, &nr_map))

		return;

	e820.nr_map = nr_map;

	printk(KERN_INFO "modified physical RAM map:\n");

	print_memory_map("modified");

}

arch/x86/kernel/setup_32.c

+6 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ 


#include <video/edid.h>



#include <asm/mtrr.h>

#include <asm/apic.h>

#include <asm/e820.h>

#include <asm/mpspec.h>
@@ -758,6 +759,11 @@ void __init setup_arch(char **cmdline_p) 


	max_low_pfn = setup_memory();



	/* update e820 for memory not covered by WB MTRRs */

	mtrr_bp_init();

	if (mtrr_trim_uncached_memory(max_pfn))

		max_low_pfn = setup_memory();



#ifdef CONFIG_VMI

	/*

	 * Must be after max_low_pfn is determined, and before kernel