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| author | Keir Fraser <keir.fraser@citrix.com> | 2010-07-21 08:43:35 +0100 |
|---|---|---|
| committer | Keir Fraser <keir.fraser@citrix.com> | 2010-07-21 08:43:35 +0100 |
| commit | 077b04c0350e1bc20a41b06dad49a3e2a72ca8c8 (patch) | |
| tree | 45b9720eb55829c24ce91535f497dc07a90052f0 /xen/arch/x86/e820.c | |
| parent | 91dd929995d93d49a3b391e73e299023a49dba47 (diff) | |
| download | xen-077b04c0350e1bc20a41b06dad49a3e2a72ca8c8.tar.gz xen-077b04c0350e1bc20a41b06dad49a3e2a72ca8c8.tar.bz2 xen-077b04c0350e1bc20a41b06dad49a3e2a72ca8c8.zip | |
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@Oracle.Com>
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
Diffstat (limited to 'xen/arch/x86/e820.c')
| -rw-r--r-- | xen/arch/x86/e820.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/xen/arch/x86/e820.c b/xen/arch/x86/e820.c index fb76b5c51a..a9276cd17c 100644 --- a/xen/arch/x86/e820.c +++ b/xen/arch/x86/e820.c @@ -10,10 +10,20 @@ #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; boolean_param("e820-mtrr-clip", e820_mtrr_clip); @@ -503,7 +513,8 @@ static void __init reserve_dmi_region(void) 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); @@ -513,6 +524,17 @@ static void __init machine_specific_memory_setup( 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, "Only the first %lu GB of the physical memory map " |