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x86_32: trim memory by updating e820

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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: Yinghai Lu <yinghai.lu@sun.com>
Tested-by: Justin Piszcz <jpiszcz@lucidpixels.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Yinghai Lu
2008-01-30 13:33:32 +01:00
committed by Ingo Molnar
parent 11201e603d
commit 093af8d7f0
6 changed files with 64 additions and 10 deletions
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30
arch/x86/kernel/cpu/common.c
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@@ -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)