This patch provides an enhancement to kexec/kdump. It implements
the following features:
- Backup/restore memory used by the original kernel before/after
kexec.
- Save/restore CPU state before/after kexec.
The features of this patch can be used as a general method to call
program in physical mode (paging turning off). This can be used to
call BIOS code under Linux.
kexec-tools needs to be patched to support kexec jump. The patches and
the precompiled kexec can be download from the following URL:
source: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-src_git_kh10.tar.bz2
patches: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-patches_git_kh10.tar.bz2
binary: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec_git_kh10
Usage example of calling some physical mode code and return:
1. Compile and install patched kernel with following options selected:
CONFIG_X86_32=y
CONFIG_KEXEC=y
CONFIG_PM=y
CONFIG_KEXEC_JUMP=y
2. Build patched kexec-tool or download the pre-built one.
3. Build some physical mode executable named such as "phy_mode"
4. Boot kernel compiled in step 1.
5. Load physical mode executable with /sbin/kexec. The shell command
line can be as follow:
/sbin/kexec --load-preserve-context --args-none phy_mode
6. Call physical mode executable with following shell command line:
/sbin/kexec -e
Implementation point:
To support jumping without reserving memory. One shadow backup page
(source page) is allocated for each page used by kexeced code image
(destination page). When do kexec_load, the image of kexeced code is
loaded into source pages, and before executing, the destination pages
and the source pages are swapped, so the contents of destination pages
are backupped. Before jumping to the kexeced code image and after
jumping back to the original kernel, the destination pages and the
source pages are swapped too.
C ABI (calling convention) is used as communication protocol between
kernel and called code.
A flag named KEXEC_PRESERVE_CONTEXT for sys_kexec_load is added to
indicate that the loaded kernel image is used for jumping back.
ChangeLog:
v12:
- Add a Kconfig option KEXEC_JUMP to resolve the dependency problem.
- Merge kexec_jump() into kernel_kexec().
v10:
- Device state save/restore related code is split into another patch
because it depends on devices hibernation/restore callback and prone
to be changed.
- C ABI (calling convention) is used as communication protocol between
kernel and called code.
- Code cleanup: CPU state save/restore code goes in relocate_kernel().
v9:
- pm_mutex is locked during kexec jump to avoid potential conflict
between kexec jump and suspend/resume/hibernation.
- Split /dev/oldmem writing and kimagecore patch out, keep only the
core function.
v8:
- Split kexec jump patchset from kexec based hibernation patchset.
- Merge various KEXEC_PRESERVE_* flags into one KEXEC_PRESERVE_CONTEXT
because there is no need for such subtle control.
- Delete variable argument based "kernel to kernel" communication
mechanism from basic kexec jump patchset.
v7:
- Refactor kexec jump to be a command driven programming model.
- Use kexec_lock to do synchronization.
v6:
- Refactor kexec jump to be a general facility to call real mode code.
v5:
- A flag (KEXEC_JUMP_BACK) is added to indicate the loaded kernel
image is used for jumping back. The reboot command for jumping back
is removed. This interface is more stable (proposed by Eric
Biederman).
- NX bit handling support for kexec is added.
- Merge machine_kexec and machine_kexec_jump, remove NO_RET attribute
from machine_kexec.
- Passing jump back entry to kexeced kernel via kernel command line
(parsed by user space tool via /proc/cmdline instead of
kernel). Original corresponding boot parameter and sysfs code is
removed.
v4:
- Two reboot command are merged back to one because the underlying
implementation is same.
- Jumping without reserving memory is implemented. As a side effect,
two direction jumping is implemented.
- A jump back protocol is defined and documented. The original kernel
and kexeced kernel are more independent from each other.
- The CPU state save/restore code are merged into relocate_kernel.S.
v3:
- The reboot command LINUX_REBOOT_CMD_KJUMP is split into to two
reboot command to reflect the different function.
- Document is added for added kernel parameters.
- /sys/kernel/kexec_jump_buf_pfn is made writable, it is used for
memory image restoring.
- Console restoring after jumping back is implemented.
v2:
- The kexec jump implementation is put into the kexec/kdump framework
instead of software suspend framework. The device and CPU state
save/restore code of software suspend is called when needed.
- The same code path is used for both kexec a new kernel and jump back
to original kernel.
Now, only the i386 architecture is supported. The patchset is based on
Linux kernel 2.6.26-rc8-mm1, and has been tested on IBM T42.
Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>
---
arch/powerpc/kernel/machine_kexec.c | 2
arch/sh/kernel/machine_kexec.c | 2
arch/x86/Kconfig | 7 +
arch/x86/kernel/machine_kexec_32.c | 27 ++++-
arch/x86/kernel/machine_kexec_64.c | 2
arch/x86/kernel/relocate_kernel_32.S | 174 ++++++++++++++++++++++++++++++-----
include/asm-x86/kexec.h | 18 ++-
include/linux/kexec.h | 17 ++-
kernel/kexec.c | 57 +++++++++++
kernel/sys.c | 31 +-----
10 files changed, 269 insertions(+), 68 deletions(-)
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -22,6 +22,7 @@
#include <asm/cpufeature.h>
#include <asm/desc.h>
#include <asm/system.h>
+#include <asm/cacheflush.h>
#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
static u32 kexec_pgd[1024] PAGE_ALIGNED;
@@ -85,10 +86,12 @@ static void load_segments(void)
* reboot code buffer to allow us to avoid allocations
* later.
*
- * Currently nothing.
+ * Make control page executable.
*/
int machine_kexec_prepare(struct kimage *image)
{
+ if (nx_enabled)
+ set_pages_x(image->control_code_page, 1);
return 0;
}
@@ -98,16 +101,24 @@ int machine_kexec_prepare(struct kimage
*/
void machine_kexec_cleanup(struct kimage *image)
{
+ if (nx_enabled)
+ set_pages_nx(image->control_code_page, 1);
}
/*
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
-NORET_TYPE void machine_kexec(struct kimage *image)
+void machine_kexec(struct kimage *image)
{
unsigned long page_list[PAGES_NR];
void *control_page;
+ asmlinkage unsigned long
+ (*relocate_kernel_ptr)(unsigned long indirection_page,
+ unsigned long control_page,
+ unsigned long start_address,
+ unsigned int has_pae,
+ unsigned int preserve_context);
tracer_disable();
@@ -115,10 +126,11 @@ NORET_TYPE void machine_kexec(struct kim
local_irq_disable();
control_page = page_address(image->control_code_page);
- memcpy(control_page, relocate_kernel, PAGE_SIZE);
+ memcpy(control_page, relocate_kernel, PAGE_SIZE/2);
+ relocate_kernel_ptr = control_page;
page_list[PA_CONTROL_PAGE] = __pa(control_page);
- page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
+ page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
page_list[PA_PGD] = __pa(kexec_pgd);
page_list[VA_PGD] = (unsigned long)kexec_pgd;
#ifdef CONFIG_X86_PAE
@@ -131,6 +143,7 @@ NORET_TYPE void machine_kexec(struct kim
page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
page_list[PA_PTE_1] = __pa(kexec_pte1);
page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
+ page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) << PAGE_SHIFT);
/* The segment registers are funny things, they have both a
* visible and an invisible part. Whenever the visible part is
@@ -149,8 +162,10 @@ NORET_TYPE void machine_kexec(struct kim
set_idt(phys_to_virt(0),0);
/* now call it */
- relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
- image->start, cpu_has_pae);
+ image->start = relocate_kernel_ptr((unsigned long)image->head,
+ (unsigned long)page_list,
+ image->start, cpu_has_pae,
+ image->preserve_context);
}
void arch_crash_save_vmcoreinfo(void)
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -83,6 +83,7 @@ struct kimage {
unsigned long start;
struct page *control_code_page;
+ struct page *swap_page;
unsigned long nr_segments;
struct kexec_segment segment[KEXEC_SEGMENT_MAX];
@@ -98,18 +99,20 @@ struct kimage {
unsigned int type : 1;
#define KEXEC_TYPE_DEFAULT 0
#define KEXEC_TYPE_CRASH 1
+ unsigned int preserve_context : 1;
};
/* kexec interface functions */
-extern NORET_TYPE void machine_kexec(struct kimage *image) ATTRIB_NORET;
+extern void machine_kexec(struct kimage *image);
extern int machine_kexec_prepare(struct kimage *image);
extern void machine_kexec_cleanup(struct kimage *image);
extern asmlinkage long sys_kexec_load(unsigned long entry,
unsigned long nr_segments,
struct kexec_segment __user *segments,
unsigned long flags);
+extern int kernel_kexec(void);
#ifdef CONFIG_COMPAT
extern asmlinkage long compat_sys_kexec_load(unsigned long entry,
unsigned long nr_segments,
@@ -156,8 +159,9 @@ extern struct kimage *kexec_crash_image;
#define kexec_flush_icache_page(page)
#endif
-#define KEXEC_ON_CRASH 0x00000001
-#define KEXEC_ARCH_MASK 0xffff0000
+#define KEXEC_ON_CRASH 0x00000001
+#define KEXEC_PRESERVE_CONTEXT 0x00000002
+#define KEXEC_ARCH_MASK 0xffff0000
/* These values match the ELF architecture values.
* Unless there is a good reason that should continue to be the case.
@@ -174,7 +178,12 @@ extern struct kimage *kexec_crash_image;
#define KEXEC_ARCH_MIPS_LE (10 << 16)
#define KEXEC_ARCH_MIPS ( 8 << 16)
-#define KEXEC_FLAGS (KEXEC_ON_CRASH) /* List of defined/legal kexec flags */
+/* List of defined/legal kexec flags */
+#ifndef CONFIG_KEXEC_JUMP
+#define KEXEC_FLAGS KEXEC_ON_CRASH
+#else
+#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT)
+#endif
#define VMCOREINFO_BYTES (4096)
#define VMCOREINFO_NOTE_NAME "VMCOREINFO"
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -24,6 +24,8 @@
#include <linux/utsrelease.h>
#include <linux/utsname.h>
#include <linux/numa.h>
+#include <linux/suspend.h>
+#include <linux/device.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -242,6 +244,12 @@ static int kimage_normal_alloc(struct ki
goto out;
}
+ image->swap_page = kimage_alloc_control_pages(image, 0);
+ if (!image->swap_page) {
+ printk(KERN_ERR "Could not allocate swap buffer\n");
+ goto out;
+ }
+
result = 0;
out:
if (result == 0)
@@ -986,6 +994,8 @@ asmlinkage long sys_kexec_load(unsigned
if (result)
goto out;
+ if (flags & KEXEC_PRESERVE_CONTEXT)
+ image->preserve_context = 1;
result = machine_kexec_prepare(image);
if (result)
goto out;
@@ -1411,3 +1421,50 @@ static int __init crash_save_vmcoreinfo_
}
module_init(crash_save_vmcoreinfo_init)
+
+/**
+ * kernel_kexec - reboot the system
+ *
+ * Move into place and start executing a preloaded standalone
+ * executable. If nothing was preloaded return an error.
+ */
+int kernel_kexec(void)
+{
+ int error = 0;
+
+ if (xchg(&kexec_lock, 1))
+ return -EBUSY;
+ if (!kexec_image) {
+ error = -EINVAL;
+ goto Unlock;
+ }
+
+ if (kexec_image->preserve_context) {
+#ifdef CONFIG_KEXEC_JUMP
+ local_irq_disable();
+ save_processor_state();
+#endif
+ } else {
+ blocking_notifier_call_chain(&reboot_notifier_list,
+ SYS_RESTART, NULL);
+ system_state = SYSTEM_RESTART;
+ device_shutdown();
+ sysdev_shutdown();
+ printk(KERN_EMERG "Starting new kernel\n");
+ machine_shutdown();
+ }
+
+ machine_kexec(kexec_image);
+
+ if (kexec_image->preserve_context) {
+#ifdef CONFIG_KEXEC_JUMP
+ restore_processor_state();
+ local_irq_enable();
+#endif
+ }
+
+ Unlock:
+ xchg(&kexec_lock, 0);
+
+ return error;
+}
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -301,26 +301,6 @@ void kernel_restart(char *cmd)
}
EXPORT_SYMBOL_GPL(kernel_restart);
-/**
- * kernel_kexec - reboot the system
- *
- * Move into place and start executing a preloaded standalone
- * executable. If nothing was preloaded return an error.
- */
-static void kernel_kexec(void)
-{
-#ifdef CONFIG_KEXEC
- struct kimage *image;
- image = xchg(&kexec_image, NULL);
- if (!image)
- return;
- kernel_restart_prepare(NULL);
- printk(KERN_EMERG "Starting new kernel\n");
- machine_shutdown();
- machine_kexec(image);
-#endif
-}
-
static void kernel_shutdown_prepare(enum system_states state)
{
blocking_notifier_call_chain(&reboot_notifier_list,
@@ -425,10 +405,15 @@ asmlinkage long sys_reboot(int magic1, i
kernel_restart(buffer);
break;
+#ifdef CONFIG_KEXEC
case LINUX_REBOOT_CMD_KEXEC:
- kernel_kexec();
- unlock_kernel();
- return -EINVAL;
+ {
+ int ret;
+ ret = kernel_kexec();
+ unlock_kernel();
+ return ret;
+ }
+#endif
#ifdef CONFIG_HIBERNATION
case LINUX_REBOOT_CMD_SW_SUSPEND:
--- a/arch/x86/kernel/relocate_kernel_32.S
+++ b/arch/x86/kernel/relocate_kernel_32.S
@@ -20,11 +20,44 @@
#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
#define PAE_PGD_ATTR (_PAGE_PRESENT)
+/* control_page + PAGE_SIZE/2 ~ control_page + PAGE_SIZE * 3/4 are
+ * used to save some data for jumping back
+ */
+#define DATA(offset) (PAGE_SIZE/2+(offset))
+
+/* Minimal CPU state */
+#define ESP DATA(0x0)
+#define CR0 DATA(0x4)
+#define CR3 DATA(0x8)
+#define CR4 DATA(0xc)
+
+/* other data */
+#define CP_VA_CONTROL_PAGE DATA(0x10)
+#define CP_PA_PGD DATA(0x14)
+#define CP_PA_SWAP_PAGE DATA(0x18)
+#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c)
+
.text
.align PAGE_SIZE
.globl relocate_kernel
relocate_kernel:
- movl 8(%esp), %ebp /* list of pages */
+ /* Save the CPU context, used for jumping back */
+
+ pushl %ebx
+ pushl %esi
+ pushl %edi
+ pushl %ebp
+ pushf
+
+ movl 20+8(%esp), %ebp /* list of pages */
+ movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
+ movl %esp, ESP(%edi)
+ movl %cr0, %eax
+ movl %eax, CR0(%edi)
+ movl %cr3, %eax
+ movl %eax, CR3(%edi)
+ movl %cr4, %eax
+ movl %eax, CR4(%edi)
#ifdef CONFIG_X86_PAE
/* map the control page at its virtual address */
@@ -138,15 +171,25 @@ relocate_kernel:
relocate_new_kernel:
/* read the arguments and say goodbye to the stack */
- movl 4(%esp), %ebx /* page_list */
- movl 8(%esp), %ebp /* list of pages */
- movl 12(%esp), %edx /* start address */
- movl 16(%esp), %ecx /* cpu_has_pae */
+ movl 20+4(%esp), %ebx /* page_list */
+ movl 20+8(%esp), %ebp /* list of pages */
+ movl 20+12(%esp), %edx /* start address */
+ movl 20+16(%esp), %ecx /* cpu_has_pae */
+ movl 20+20(%esp), %esi /* preserve_context */
/* zero out flags, and disable interrupts */
pushl $0
popfl
+ /* save some information for jumping back */
+ movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
+ movl %edi, CP_VA_CONTROL_PAGE(%edi)
+ movl PTR(PA_PGD)(%ebp), %eax
+ movl %eax, CP_PA_PGD(%edi)
+ movl PTR(PA_SWAP_PAGE)(%ebp), %eax
+ movl %eax, CP_PA_SWAP_PAGE(%edi)
+ movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
+
/* get physical address of control page now */
/* this is impossible after page table switch */
movl PTR(PA_CONTROL_PAGE)(%ebp), %edi
@@ -197,8 +240,90 @@ identity_mapped:
xorl %eax, %eax
movl %eax, %cr3
+ movl CP_PA_SWAP_PAGE(%edi), %eax
+ pushl %eax
+ pushl %ebx
+ call swap_pages
+ addl $8, %esp
+
+ /* To be certain of avoiding problems with self-modifying code
+ * I need to execute a serializing instruction here.
+ * So I flush the TLB, it's handy, and not processor dependent.
+ */
+ xorl %eax, %eax
+ movl %eax, %cr3
+
+ /* set all of the registers to known values */
+ /* leave %esp alone */
+
+ testl %esi, %esi
+ jnz 1f
+ xorl %edi, %edi
+ xorl %eax, %eax
+ xorl %ebx, %ebx
+ xorl %ecx, %ecx
+ xorl %edx, %edx
+ xorl %esi, %esi
+ xorl %ebp, %ebp
+ ret
+1:
+ popl %edx
+ movl CP_PA_SWAP_PAGE(%edi), %esp
+ addl $PAGE_SIZE, %esp
+2:
+ call *%edx
+
+ /* get the re-entry point of the peer system */
+ movl 0(%esp), %ebp
+ call 1f
+1:
+ popl %ebx
+ subl $(1b - relocate_kernel), %ebx
+ movl CP_VA_CONTROL_PAGE(%ebx), %edi
+ lea PAGE_SIZE(%ebx), %esp
+ movl CP_PA_SWAP_PAGE(%ebx), %eax
+ movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
+ pushl %eax
+ pushl %edx
+ call swap_pages
+ addl $8, %esp
+ movl CP_PA_PGD(%ebx), %eax
+ movl %eax, %cr3
+ movl %cr0, %eax
+ orl $(1<<31), %eax
+ movl %eax, %cr0
+ lea PAGE_SIZE(%edi), %esp
+ movl %edi, %eax
+ addl $(virtual_mapped - relocate_kernel), %eax
+ pushl %eax
+ ret
+
+virtual_mapped:
+ movl CR4(%edi), %eax
+ movl %eax, %cr4
+ movl CR3(%edi), %eax
+ movl %eax, %cr3
+ movl CR0(%edi), %eax
+ movl %eax, %cr0
+ movl ESP(%edi), %esp
+ movl %ebp, %eax
+
+ popf
+ popl %ebp
+ popl %edi
+ popl %esi
+ popl %ebx
+ ret
+
/* Do the copies */
- movl %ebx, %ecx
+swap_pages:
+ movl 8(%esp), %edx
+ movl 4(%esp), %ecx
+ pushl %ebp
+ pushl %ebx
+ pushl %edi
+ pushl %esi
+ movl %ecx, %ebx
jmp 1f
0: /* top, read another word from the indirection page */
@@ -226,27 +351,28 @@ identity_mapped:
movl %ecx, %esi /* For every source page do a copy */
andl $0xfffff000, %esi
+ movl %edi, %eax
+ movl %esi, %ebp
+
+ movl %edx, %edi
movl $1024, %ecx
rep ; movsl
- jmp 0b
-
-3:
- /* To be certain of avoiding problems with self-modifying code
- * I need to execute a serializing instruction here.
- * So I flush the TLB, it's handy, and not processor dependent.
- */
- xorl %eax, %eax
- movl %eax, %cr3
+ movl %ebp, %edi
+ movl %eax, %esi
+ movl $1024, %ecx
+ rep ; movsl
- /* set all of the registers to known values */
- /* leave %esp alone */
+ movl %eax, %edi
+ movl %edx, %esi
+ movl $1024, %ecx
+ rep ; movsl
- xorl %eax, %eax
- xorl %ebx, %ebx
- xorl %ecx, %ecx
- xorl %edx, %edx
- xorl %esi, %esi
- xorl %edi, %edi
- xorl %ebp, %ebp
+ lea PAGE_SIZE(%ebp), %esi
+ jmp 0b
+3:
+ popl %esi
+ popl %edi
+ popl %ebx
+ popl %ebp
ret
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -181,7 +181,7 @@ void machine_kexec_cleanup(struct kimage
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
-NORET_TYPE void machine_kexec(struct kimage *image)
+void machine_kexec(struct kimage *image)
{
unsigned long page_list[PAGES_NR];
void *control_page;
--- a/arch/sh/kernel/machine_kexec.c
+++ b/arch/sh/kernel/machine_kexec.c
@@ -70,7 +70,7 @@ static void kexec_info(struct kimage *im
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
-NORET_TYPE void machine_kexec(struct kimage *image)
+void machine_kexec(struct kimage *image)
{
unsigned long page_list;
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -48,7 +48,7 @@ void machine_kexec_cleanup(struct kimage
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
-NORET_TYPE void machine_kexec(struct kimage *image)
+void machine_kexec(struct kimage *image)
{
if (ppc_md.machine_kexec)
ppc_md.machine_kexec(image);
--- a/include/asm-x86/kexec.h
+++ b/include/asm-x86/kexec.h
@@ -10,14 +10,15 @@
# define VA_PTE_0 5
# define PA_PTE_1 6
# define VA_PTE_1 7
+# define PA_SWAP_PAGE 8
# ifdef CONFIG_X86_PAE
-# define PA_PMD_0 8
-# define VA_PMD_0 9
-# define PA_PMD_1 10
-# define VA_PMD_1 11
-# define PAGES_NR 12
+# define PA_PMD_0 9
+# define VA_PMD_0 10
+# define PA_PMD_1 11
+# define VA_PMD_1 12
+# define PAGES_NR 13
# else
-# define PAGES_NR 8
+# define PAGES_NR 9
# endif
#else
# define PA_CONTROL_PAGE 0
@@ -152,11 +153,12 @@ static inline void crash_setup_regs(stru
}
#ifdef CONFIG_X86_32
-asmlinkage NORET_TYPE void
+asmlinkage unsigned long
relocate_kernel(unsigned long indirection_page,
unsigned long control_page,
unsigned long start_address,
- unsigned int has_pae) ATTRIB_NORET;
+ unsigned int has_pae,
+ unsigned int preserve_context);
#else
NORET_TYPE void
relocate_kernel(unsigned long indirection_page,
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1273,6 +1273,13 @@ config CRASH_DUMP
(CONFIG_RELOCATABLE=y).
For more details see Documentation/kdump/kdump.txt
+config KEXEC_JUMP
+ bool "kexec jump (EXPERIMENTAL)"
+ depends on EXPERIMENTAL
+ depends on KEXEC && PM_SLEEP && X86_32
+ help
+ Invoke code in physical address mode via KEXEC
+
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
default "0x1000000" if X86_NUMAQ
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