From 093af8d7f0ba3c6be1485973508584ef081e9f93 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 30 Jan 2008 13:33:32 +0100 Subject: 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: Yinghai Lu Tested-by: Justin Piszcz Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/cpu/mtrr/main.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'arch/x86/kernel/cpu/mtrr') diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c index ccd36ed2187..ac4b6338f3f 100644 --- a/arch/x86/kernel/cpu/mtrr/main.c +++ b/arch/x86/kernel/cpu/mtrr/main.c @@ -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 -- cgit v1.2.3