lkml.org 
[lkml]   [2007]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[x86 setup 25/33] Memory probing support for the new x86 setup code
Date
From: H. Peter Anvin <hpa@zytor.com>

Probe memory (INT 15h: E820, E801, 88).

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
arch/i386/boot/memory.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 99 insertions(+), 0 deletions(-)
create mode 100644 arch/i386/boot/memory.c
diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c
new file mode 100644
index 0000000..1a2e62d
--- /dev/null
+++ b/arch/i386/boot/memory.c
@@ -0,0 +1,99 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright 2007 rPath, Inc. - All Rights Reserved
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * arch/i386/boot/memory.c
+ *
+ * Memory detection code
+ */
+
+#include "boot.h"
+
+#define SMAP 0x534d4150 /* ASCII "SMAP" */
+
+static int detect_memory_e820(void)
+{
+ u32 next = 0;
+ u32 size, id;
+ u8 err;
+ struct e820entry *desc = boot_params.e820_map;
+
+ do {
+ size = sizeof(struct e820entry);
+ id = SMAP;
+ asm("int $0x15; setc %0"
+ : "=am" (err), "+b" (next), "+d" (id), "+c" (size),
+ "=m" (*desc)
+ : "D" (desc), "a" (0xe820));
+
+ if (err || id != SMAP)
+ break;
+
+ boot_params.e820_entries++;
+ desc++;
+ } while (next && boot_params.e820_entries < E820MAX);
+
+ return boot_params.e820_entries;
+}
+
+static int detect_memory_e801(void)
+{
+ u16 ax, bx, cx, dx;
+ u8 err;
+
+ bx = cx = dx = 0;
+ ax = 0xe801;
+ asm("stc; int $0x15; setc %0"
+ : "=m" (err), "+a" (ax), "+b" (bx), "+c" (cx), "+d" (dx));
+
+ if (err)
+ return -1;
+
+ /* Do we really need to do this? */
+ if (cx || dx) {
+ ax = cx;
+ bx = dx;
+ }
+
+ if (ax > 15*1024)
+ return -1; /* Bogus! */
+
+ /* This ignores memory above 16MB if we have a memory hole
+ there. If someone actually finds a machine with a memory
+ hole at 16MB and no support for 0E820h they should probably
+ generate a fake e820 map. */
+ boot_params.alt_mem_k = (ax == 15*1024) ? (dx << 6)+ax : ax;
+
+ return 0;
+}
+
+static int detect_memory_88(void)
+{
+ u16 ax;
+ u8 err;
+
+ ax = 0x8800;
+ asm("stc; int $0x15; setc %0" : "=bcdm" (err), "+a" (ax));
+
+ boot_params.screen_info.ext_mem_k = ax;
+
+ return -err;
+}
+
+int detect_memory(void)
+{
+ if (detect_memory_e820() > 0)
+ return 0;
+
+ if (!detect_memory_e801())
+ return 0;
+
+ return detect_memory_88();
+}
--
1.5.2.2
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-07-11 21:33    [from the cache]
©2003-2011 Jasper Spaans