[Patch 3/8] x86: implement crashkernel=auto

Amerigo Wang
2009-08-21T06:55:27Z

Implement "crashkernel=auto" for x86 first, other arch will be added in the
following patches.

The kernel will modify this command line with the actually reserved size,
in case of breaking any user-space programs.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>

---

Index: linux-2.6/kernel/kexec.c
===================================================================
--- linux-2.6.orig/kernel/kexec.c
+++ linux-2.6/kernel/kexec.c
@@ -37,6 +37,7 @@
#include <asm/io.h>
#include <asm/system.h>
#include <asm/sections.h>
+#include <asm/setup.h>

/* Per cpu memory for storing cpu states in case of system crash. */
note_buf_t* crash_notes;
@@ -1297,6 +1298,39 @@ int __init parse_crashkernel(char *cm

ck_cmdline += 12; /* strlen("crashkernel=") */

+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+ if (strncmp(ck_cmdline, "auto", 4) == 0) {
+ unsigned long long size;
+ int len;
+ char tmp[32];
+
+ size = arch_default_crash_size(system_ram);
+ if (size != 0) {
+ *crash_size = size;
+ *crash_base = arch_default_crash_base();
+ len = scnprintf(tmp, sizeof(tmp), "%luM@%luM",
+ (unsigned long)(*crash_size)>>20,
+ (unsigned long)(*crash_base)>>20);
+ /* 'len' can't be <= 4. */
+ if (likely((len - 4 + strlen(cmdline))
+ < COMMAND_LINE_SIZE - 1)) {
+ memmove(ck_cmdline + len, ck_cmdline + 4,
+ strlen(cmdline) - (ck_cmdline + 4 - cmdline) + 1);
+ memcpy(ck_cmdline, tmp, len);
+ }
+ return 0;
+ } else {
+ /*
+ * We can't reserve memory auotmatcally,
+ * remove "crashkernel=auto" from cmdline.
+ */
+ ck_cmdline += 4; /* strlen("auto") */
+ memmove(ck_cmdline - 16, ck_cmdline,
+ strlen(cmdline) - (ck_cmdline - cmdline) + 1);
+ return -ENOMEM;
+ }
+ }
+#endif
/*
* if the commandline contains a ':', then that's the extended
* syntax -- if not, it must be the classic syntax
Index: linux-2.6/arch/x86/include/asm/kexec.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/kexec.h
+++ linux-2.6/arch/x86/include/asm/kexec.h
@@ -23,6 +23,7 @@

#include <asm/page.h>
#include <asm/ptrace.h>
+#include <asm-generic/kexec.h>

/*
* KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
Index: linux-2.6/include/asm-generic/kexec.h
===================================================================
--- /dev/null
+++ linux-2.6/include/asm-generic/kexec.h
@@ -0,0 +1,42 @@
+#ifndef _ASM_GENERIC_KEXEC_H
+#define _ASM_GENERIC_KEXEC_H
+
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+
+#ifndef KEXEC_AUTO_RESERVED_SIZE
+#define KEXEC_AUTO_RESERVED_SIZE (1ULL<<27) /* 128M */
+#endif
+#ifndef KEXEC_AUTO_THRESHOLD
+#define KEXEC_AUTO_THRESHOLD (1ULL<<32) /* 4G */
+#endif
+
+#ifndef ARCH_HAS_DEFAULT_CRASH_SIZE
+static inline
+unsigned long long arch_default_crash_size(unsigned long long total_size)
+{
+ if (total_size < KEXEC_AUTO_THRESHOLD)
+ return 0;
+ else {
+#ifdef CONFIG_64BIT
+ if (total_size > 1ULL<<40) /* 1TB */
+ return KEXEC_AUTO_RESERVED_SIZE
+ * (1ULL<<40 / KEXEC_AUTO_THRESHOLD);
+ return 1ULL<<ilog2(roundup(total_size/32, 1ULL<<21));
+#else
+ return KEXEC_AUTO_RESERVED_SIZE;
+#endif
+ }
+}
+#endif
+#ifndef ARCH_HAS_DEFAULT_CRASH_BASE
+static inline
+unsigned long long arch_default_crash_base(void)
+{
+ /* 0 means find the base address automatically. */
+ return 0;
+}
+#endif
+
+#endif /* CONFIG_KEXEC_AUTO_RESERVE */
+
+#endif