linux-kernel - Re: [PATCH] Prevent reserving RAM in the region already reserved by BIOS

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Date:	Wed, 19 May 2010 17:07:01 -0700
From:	Yinghai <yinghai.lu@...cle.com>
To:	Mathieu Rondonneau <mathieu.rondonneau@...il.com>
CC:	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] Prevent reserving RAM in the region already reserved
 by  BIOS

On 05/19/2010 05:01 PM, Mathieu Rondonneau wrote:
> it' s not in ISA space.
> once loading the NVIDIA driver, the warnign oops shows up.
> 4K starting at 0x9f800 (i.e. to 0xa007ff) overlap with the ISA space
> (starting at 0xa0000).
> 
> When I don' t load the driver, no oops.
> So I am assuming nvidia driver request 4K of memory, that happens to
> be available in the bios area.
> 
> I think that there is a check missing somewhere to report that
> available RAM buffer is already reserved (by BIOS) so we need to get
> it from somewhere else.

please check if this patch fix the problem.

Subject: [PATCH] x86: Align e820 ram range to page

To workaround wrong BIOS memory map.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 arch/x86/kernel/e820.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -910,6 +910,47 @@ static int __init parse_memmap_opt(char
 }
 early_param("memmap", parse_memmap_opt);
 
+static void __init e820_align_ram_page(void)
+{
+	int i;
+	bool changed = false;;
+
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *entry = &e820.map[i];
+		u64 start, end;
+		u64 start_aligned, end_aligned;
+
+		if (entry->type != E820_RAM)
+			continue;
+
+		start = entry->addr;
+		end = start + entry->size;
+
+		start_aligned = round_up(start, PAGE_SIZE);
+		end_aligned = round_down(end, PAGE_SIZE);
+
+		if (end_aligned <= start_aligned) {
+			e820_update_range(start, end - start, E820_RAM, E820_RESERVED);
+			changed = true;
+			continue;
+		}
+		if (start < start_aligned) {
+			e820_update_range(start, start_aligned - start, E820_RAM, E820_RESERVED);
+			changed = true;
+		}
+		if (end_aligned < end) {
+			e820_update_range(end_aligned, end - end_aligned, E820_RAM, E820_RESERVED);
+			changed = true;
+		}
+	}
+
+	if (changed) {
+		sanitize_e820_map();
+		printk(KERN_INFO "aligned physical RAM map:\n");
+		e820_print_map("aligned");
+	}
+}
+
 void __init finish_e820_parsing(void)
 {
 	if (userdef) {
@@ -922,6 +963,9 @@ void __init finish_e820_parsing(void)
 		printk(KERN_INFO "user-defined physical RAM map:\n");
 		e820_print_map("user");
 	}
+
+	/* In case, We have RAM entres that are not PAGE aligned */
+	e820_align_ram_page();
 }
 
 static inline const char *e820_type_to_string(int e820_type)
--
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