[PATCH] powerpc: Add CONFIG_CRASH_DUMP
This patch adds a Kconfig variable, CONFIG_CRASH_DUMP, which configures the
built kernel for use as a Kdump kernel.
Currently "all" this involves is changing the value of KERNELBASE to 32 MB.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2c1186a..773b880 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -379,6 +379,17 @@
bool
default y
+config CRASH_DUMP
+ bool "kernel crash dumps (EXPERIMENTAL)"
+ depends on PPC_MULTIPLATFORM
+ depends on EXPERIMENTAL
+ help
+ Build a kernel suitable for use as a kdump capture kernel.
+ The kernel will be linked at a different address than normal, and
+ so can only be used for Kdump.
+
+ Don't change this unless you know what you are doing.
+
config IBMVIO
depends on PPC_PSERIES || PPC_ISERIES
bool
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 65603e9..6509dd7 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -512,6 +512,9 @@
ppc64_caches.iline_size);
printk("htab_address = 0x%p\n", htab_address);
printk("htab_hash_mask = 0x%lx\n", htab_hash_mask);
+#if PHYSICAL_START > 0
+ printk("physical_start = 0x%x\n", PHYSICAL_START);
+#endif
printk("-----------------------------------------------------\n");
mm_init_ppc64();
diff --git a/include/asm-powerpc/page.h b/include/asm-powerpc/page.h
index 4696bdb..76d7cb4 100644
--- a/include/asm-powerpc/page.h
+++ b/include/asm-powerpc/page.h
@@ -51,8 +51,16 @@
*
* If you want to test if something's a kernel address, use is_kernel_addr().
*/
+
+#ifdef CONFIG_CRASH_DUMP
+/* Kdump kernel runs at 32 MB, change at your peril. */
+#define PHYSICAL_START 0x2000000
+#else
+#define PHYSICAL_START 0x0
+#endif
+
#define PAGE_OFFSET ASM_CONST(CONFIG_KERNEL_START)
-#define KERNELBASE PAGE_OFFSET
+#define KERNELBASE (PAGE_OFFSET + PHYSICAL_START)
#ifdef CONFIG_DISCONTIGMEM
#define page_to_pfn(page) discontigmem_page_to_pfn(page)