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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/x86/boot/memory.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/boot/memory.c')
-rw-r--r--arch/x86/boot/memory.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c
new file mode 100644
index 0000000000..b0422b79de
--- /dev/null
+++ b/arch/x86/boot/memory.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright 2007 rPath, Inc. - All Rights Reserved
+ * Copyright 2009 Intel Corporation; author H. Peter Anvin
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Memory detection code
+ */
+
+#include "boot.h"
+
+#define SMAP 0x534d4150 /* ASCII "SMAP" */
+
+static void detect_memory_e820(void)
+{
+ int count = 0;
+ struct biosregs ireg, oreg;
+ struct boot_e820_entry *desc = boot_params.e820_table;
+ static struct boot_e820_entry 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_table));
+
+ boot_params.e820_entries = count;
+}
+
+static void detect_memory_e801(void)
+{
+ struct biosregs ireg, oreg;
+
+ initregs(&ireg);
+ ireg.ax = 0xe801;
+ intcall(0x15, &ireg, &oreg);
+
+ if (oreg.eflags & X86_EFLAGS_CF)
+ return;
+
+ /* 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; /* 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;
+ }
+}
+
+static void 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;
+}
+
+void detect_memory(void)
+{
+ detect_memory_e820();
+
+ detect_memory_e801();
+
+ detect_memory_88();
+}