# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1279699885 -3600
# Node ID 4f3a85e09c566ee4ea4a0ba2f0e6d258b58ca8ac
# Parent 11a5bcbfe9d70a1a7c83eb330fef9d3f941da813
x86: New boot option availmem= to limit usable system RAM.
Unlike mem=, this specifies the limit on usable RAM, rather than a
limit on maximum physical address of RAM.
Original patch by Sarina Canelake <sarina.canelake@xxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
xen-unstable changeset: 21837:3c00cb0d9bc4
xen-unstable date: Wed Jul 21 08:43:35 2010 +0100
---
xen/arch/x86/e820.c | 26 ++++++++++++++++++++++++--
1 files changed, 24 insertions(+), 2 deletions(-)
diff -r 11a5bcbfe9d7 -r 4f3a85e09c56 xen/arch/x86/e820.c
--- a/xen/arch/x86/e820.c Wed Jul 21 09:10:56 2010 +0100
+++ b/xen/arch/x86/e820.c Wed Jul 21 09:11:25 2010 +0100
@@ -10,9 +10,19 @@
#include <asm/mtrr.h>
#include <asm/msr.h>
-/* opt_mem: Limit of physical RAM. Any RAM beyond this point is ignored. */
+/*
+ * opt_mem: Limit maximum address of physical RAM.
+ * Any RAM beyond this address limit is ignored.
+ */
static unsigned long long __initdata opt_mem;
size_param("mem", opt_mem);
+
+/*
+ * opt_availmem: Limit maximum usable amount of physical RAM.
+ * Any RAM beyond this limited amount is ignored.
+ */
+static unsigned long long __initdata opt_availmem;
+size_param("availmem", opt_availmem);
/* opt_nomtrr_check: Don't clip ram to highest cacheable MTRR. */
static int __initdata e820_mtrr_clip = -1;
@@ -503,7 +513,8 @@ static void __init machine_specific_memo
static void __init machine_specific_memory_setup(
struct e820entry *raw, int *raw_nr)
{
- uint64_t top_of_ram;
+ uint64_t top_of_ram, size;
+ int i;
char nr = (char)*raw_nr;
sanitize_e820_map(raw, &nr);
@@ -512,6 +523,17 @@ static void __init machine_specific_memo
if ( opt_mem )
clip_to_limit(opt_mem, NULL);
+
+ if ( opt_availmem )
+ {
+ for ( i = size = 0; (i < e820.nr_map) && (size <= opt_availmem); i++ )
+ if ( e820.map[i].type == E820_RAM )
+ size += e820.map[i].size;
+ if ( size > opt_availmem )
+ clip_to_limit(
+ e820.map[i-1].addr + e820.map[i-1].size - (size-opt_availmem),
+ NULL);
+ }
#ifdef __i386__
clip_to_limit((1ULL << 30) * MACHPHYS_MBYTES,
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