[PATCH 2/2 v2] x86: reimplement mem boot option

Wen Congyang
2012-06-11T08:42:01Z

The boot option "mem=" specifies the total memory that the system can
use. But we implement it as max_addr.

The x86 system can be booted by EFI. If the user specify the boot
option "add_efi_memmap", we add all memory map from EFI, but we
donot handle the memory map according to the boot option "mem=".

This patch reimplement the boot option "mem=", and handle the memory
map after calling efi_init().

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
arch/x86/include/asm/e820.h | 1 +
arch/x86/kernel/e820.c | 36 +++++++++++++++++++++++++++++++-----
arch/x86/kernel/setup.c | 1 +
3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
index 3778256..d1bb772 100644
--- a/arch/x86/include/asm/e820.h
+++ b/arch/x86/include/asm/e820.h
@@ -127,6 +127,7 @@ extern void e820_reserve_resources(void);
extern void e820_reserve_resources_late(void);
extern void setup_memory_map(void);
extern char *default_machine_specific_memory_setup(void);
+extern void set_memlimit(void);

/*
* Returns true iff the specified range [s,e) is completely contained inside
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index cd07226..b234b25 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -48,6 +48,7 @@ unsigned long pci_mem_start = 0xaeedbabe;
EXPORT_SYMBOL(pci_mem_start);
#endif
static u64 max_addr = ~0ULL;
+static u64 mem_limit = ~0ULL;

/*
* This function checks if any part of the range <start,end> is mapped
@@ -824,8 +825,6 @@ static int userdef __initdata;
/* "mem=nopentium" disables the 4MB page tables. */
static int __init parse_memopt(char *p)
{
- u64 mem_size;
-
if (!p)
return -EINVAL;

@@ -840,16 +839,43 @@ static int __init parse_memopt(char *p)
}

userdef = 1;
- mem_size = memparse(p, &p);
+ mem_limit = memparse(p, &p);
/* don't remove all of memory when handling "mem={invalid}" param */
- if (mem_size == 0)
+ if (mem_limit == 0)
return -EINVAL;
- e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);

return 0;
}
early_param("mem", parse_memopt);

+void __init set_memlimit(void)
+{
+ u64 total_size = 0;
+ int i;
+
+ if (mem_limit == ~0ULL)
+ return;
+
+ for (i = 0; i < e820.nr_map; i++) {
+ struct e820entry *ei = &e820.map[i];
+
+ if (ei->type != E820_RAM)
+ continue;
+
+ if (total_size >= mem_limit) {
+ memset(ei, 0, sizeof(struct e820entry));
+ continue;
+ }
+
+ if (mem_limit - total_size <= ei->size)
+ ei->size = mem_limit - total_size;
+
+ total_size += ei->size;
+ }
+
+ sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
+}
+
static int __init parse_memmax_opt(char *p)
{
char *oldp;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 16be6dc..a3c4ac3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -815,6 +815,7 @@ void __init setup_arch(char **cmdline_p)

if (efi_enabled)
efi_init();
+ set_memlimit();

dmi_scan_machine();

--
1.7.1