Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / x86 / boot / memory.c

diff --git a/kernel/arch/x86/boot/memory.c b/kernel/arch/x86/boot/memory.c
new file mode 100644 (file)
index 0000000..db75d07
--- /dev/null
+++ b/kernel/arch/x86/boot/memory.c
@@ -0,0 +1,136 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright (C) 1991, 1992 Linus Torvalds
+ *   Copyright 2007 rPath, Inc. - All Rights Reserved
+ *   Copyright 2009 Intel Corporation; author H. Peter Anvin
+ *
+ *   This file is part of the Linux kernel, and is made available under
+ *   the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Memory detection code
+ */
+
+#include "boot.h"
+
+#define SMAP   0x534d4150      /* ASCII "SMAP" */
+
+static int detect_memory_e820(void)
+{
+       int count = 0;
+       struct biosregs ireg, oreg;
+       struct e820entry *desc = boot_params.e820_map;
+       static struct e820entry buf; /* static so it is zeroed */
+
+       initregs(&ireg);
+       ireg.ax  = 0xe820;
+       ireg.cx  = sizeof buf;
+       ireg.edx = SMAP;
+       ireg.di  = (size_t)&buf;
+
+       /*
+        * Note: at least one BIOS is known which assumes that the
+        * buffer pointed to by one e820 call is the same one as
+        * the previous call, and only changes modified fields.  Therefore,
+        * we use a temporary buffer and copy the results entry by entry.
+        *
+        * This routine deliberately does not try to account for
+        * ACPI 3+ extended attributes.  This is because there are
+        * BIOSes in the field which report zero for the valid bit for
+        * all ranges, and we don't currently make any use of the
+        * other attribute bits.  Revisit this if we see the extended
+        * attribute bits deployed in a meaningful way in the future.
+        */
+
+       do {
+               intcall(0x15, &ireg, &oreg);
+               ireg.ebx = oreg.ebx; /* for next iteration... */
+
+               /* BIOSes which terminate the chain with CF = 1 as opposed
+                  to %ebx = 0 don't always report the SMAP signature on
+                  the final, failing, probe. */
+               if (oreg.eflags & X86_EFLAGS_CF)
+                       break;
+
+               /* Some BIOSes stop returning SMAP in the middle of
+                  the search loop.  We don't know exactly how the BIOS
+                  screwed up the map at that point, we might have a
+                  partial map, the full map, or complete garbage, so
+                  just return failure. */
+               if (oreg.eax != SMAP) {
+                       count = 0;
+                       break;
+               }
+
+               *desc++ = buf;
+               count++;
+       } while (ireg.ebx && count < ARRAY_SIZE(boot_params.e820_map));
+
+       return boot_params.e820_entries = count;
+}
+
+static int detect_memory_e801(void)
+{
+       struct biosregs ireg, oreg;
+
+       initregs(&ireg);
+       ireg.ax = 0xe801;
+       intcall(0x15, &ireg, &oreg);
+
+       if (oreg.eflags & X86_EFLAGS_CF)
+               return -1;
+
+       /* Do we really need to do this? */
+       if (oreg.cx || oreg.dx) {
+               oreg.ax = oreg.cx;
+               oreg.bx = oreg.dx;
+       }
+
+       if (oreg.ax > 15*1024) {
+               return -1;      /* Bogus! */
+       } else if (oreg.ax == 15*1024) {
+               boot_params.alt_mem_k = (oreg.bx << 6) + oreg.ax;
+       } else {
+               /*
+                * 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 = oreg.ax;
+       }
+
+       return 0;
+}
+
+static int detect_memory_88(void)
+{
+       struct biosregs ireg, oreg;
+
+       initregs(&ireg);
+       ireg.ah = 0x88;
+       intcall(0x15, &ireg, &oreg);
+
+       boot_params.screen_info.ext_mem_k = oreg.ax;
+
+       return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */
+}
+
+int detect_memory(void)
+{
+       int err = -1;
+
+       if (detect_memory_e820() > 0)
+               err = 0;
+
+       if (!detect_memory_e801())
+               err = 0;
+
+       if (!detect_memory_88())
+               err = 0;
+
+       return err;
+}