diff options
| -rw-r--r-- | arch/i386/Kconfig | 41 | ||||
| -rw-r--r-- | include/asm-i386/boot.h | 3 |
2 files changed, 43 insertions, 1 deletions
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index 0d67a0a1151..0dfee812811 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -777,6 +777,47 @@ config CRASH_DUMP PHYSICAL_START. For more details see Documentation/kdump/kdump.txt +config PHYSICAL_START + hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP) + default "0x100000" + help + This gives the physical address where the kernel is loaded. + + If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then + bzImage will decompress itself to above physical address and + run from there. Otherwise, bzImage will run from the address where + it has been loaded by the boot loader and will ignore above physical + address. + + In normal kdump cases one does not have to set/change this option + as now bzImage can be compiled as a completely relocatable image + (CONFIG_RELOCATABLE=y) and be used to load and run from a different + address. This option is mainly useful for the folks who don't want + to use a bzImage for capturing the crash dump and want to use a + vmlinux instead. vmlinux is not relocatable hence a kernel needs + to be specifically compiled to run from a specific memory area + (normally a reserved region) and this option comes handy. + + So if you are using bzImage for capturing the crash dump, leave + the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y. + Otherwise if you plan to use vmlinux for capturing the crash dump + change this value to start of the reserved region (Typically 16MB + 0x1000000). In other words, it can be set based on the "X" value as + specified in the "crashkernel=YM@XM" command line boot parameter + passed to the panic-ed kernel. Typically this parameter is set as + crashkernel=64M@16M. Please take a look at + Documentation/kdump/kdump.txt for more details about crash dumps. + + Usage of bzImage for capturing the crash dump is recommended as + one does not have to build two kernels. Same kernel can be used + as production kernel and capture kernel. Above option should have + gone away after relocatable bzImage support is introduced. But it + is present because there are users out there who continue to use + vmlinux for dump capture. This option should go away down the + line. + + Don't change this unless you know what you are doing. + config RELOCATABLE bool "Build a relocatable kernel(EXPERIMENTAL)" depends on EXPERIMENTAL diff --git a/include/asm-i386/boot.h b/include/asm-i386/boot.h index 8ce79a6fa89..e7686d0a841 100644 --- a/include/asm-i386/boot.h +++ b/include/asm-i386/boot.h @@ -13,7 +13,8 @@ #define ASK_VGA 0xfffd /* ask for it at bootup */ /* Physical address where kenrel should be loaded. */ -#define LOAD_PHYSICAL_ADDR ((0x100000 + CONFIG_PHYSICAL_ALIGN - 1) \ +#define LOAD_PHYSICAL_ADDR ((CONFIG_PHYSICAL_START \ + + (CONFIG_PHYSICAL_ALIGN - 1)) \ & ~(CONFIG_PHYSICAL_ALIGN - 1)) #endif /* _LINUX_BOOT_H */ |