Powerpc构架系统内核和内核模块调试

说明：

此文档的目标系统为freescale MPC8349E-mITX,对其他采用powerPC,MIPS，ARM的芯片的系统亦具有参考意义。 此文档中内核调试为了简化，采用目标系统中的UBOOT初始化目标板，并通过UBOOT或者BDI2000加载内核到目标板的RAM中。

1. BDI2000配置：

下面是MPC8349E-mITX的BDI2000配置文件，

; BDI-2000 CONfiguraTIon file for the MPC8349E-mITX

; Tip: If after a reset, the BDI-2000 fails to halt at 0x100,

; you may need to power-down the bOArd for a few seconds.

[INIT]

; we use UBOOT to initialize the board

[TARGET]

CPUTYPE 8349

JTAGCLOCK 1

;STARTUP RESET

STARTUP RUN

BREAKMODE HARD

STEPMODE HWBP

BOOTADDR 0x00000100

;If you're getting Writing to workspace failed errors during flash operations,

;then try uncommenting this line instead. This moves the FLASH window to

;high memory, leaving low memory available for DDR.

RCW 0xb060a000 0x04040000 ;Set the HRCW to boot the image at 0xFE000000

MMU XLAT ;0xc0000000

PTBASE 0xf0 ;

[HOST]

IP 192.168.7.90

FILE $u-boot.bin

LOAD MANUAL

PROMPT 8349E-mITX-GP>

DUMP itx-dump.bin

[Flash]

CHIPTYPE AM29BX16

CHIPSIZE 0x800000

BUSWIDTH 16

;WORKSPACE 0x1000

FORMAT BIN 0xfe000000

;flash_image.bin is an image file of an entire 8MB flash region.

;Flash this file at 0xfe0000000 to restore all of flash.

;ERASE 0xFE000000 0x10000 127 ; 127 sectors @ 64KB each

;ERASE 0xFE7F0000 0x2000 8 ; 8 sectors @ 8KB each

;FILE $flash_image.bin

;Use these lines if you just want to flash U-Boot

ERASE 0xfe000000 0x10000? 4; Erase 384KB, each sector is 64KB

FILE? mpc8349e/u-boot131-mitx-gp.bin

[REGS]

FILE $reg8349e.def

以上配置文件的【HOST】段的IP要改为主机IP，关键的字段MMU XLAT 和PTBASE 是POWERPC和MIPS经常需要设置的，关于PTBASE的具体设置，超出本文范围，详细情况请参考BDI2000的手册

2.内核修改和配置

为了能够调试内核，需要在内核中的Makefile中增加如下调试选项：

CFLAGS 增加C代码调试选项-g –ggdb

AFLAGS 增加汇编代码调试选项：-Wa,-L -gdwarf-2

去掉CFLAGS编译选项中-fomit-frAME-pointer

GCC的-fomit-frame-pointer选项是优化函数栈回溯(stack backtrace)的，我们调试的时候需要提供函数回溯能力，所以我们要去掉这个选项，当然，有的系统系统不受它的影响，或者说它不起作用，为了统一，我们统一去掉它。

相对个案来说，我是做如下改动的：

--- Makefile 2008-07-08 03:07:38.000000000 +0800

+++ Makefile.debug 2008-07-08 03:06:04.000000000 +0800

…

-CPPFLAGS := -D__KERNEL__ $(LINUXINCLUDE)

+ifdef CONFIG_DEBUG_INFO

+

+ CPPFLAGS := -D__KERNEL__ $(LINUXINCLUDE) -g -ggdb

-CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs

+ CFLAGS := $(CPPFLAGS) -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs

-fno-strict-aliasing -fno-common

-AFLAGS := -D__ASSEMBLY__

+ AFLAGS := -D__ASSEMBLY__ -Wa,-L -gdwarf-2

+else

+ CPPFLAGS := -D__KERNEL__ $(LINUXINCLUDE)

+ CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs

+ -fno-strict-aliasing -fno-common

+ AFLAGS := -D__ASSEMBLY__

+

+endif

…

@@ -491,27 +500,33 @@

# Defaults vmlinux but it is usually overridden in the arch makefile

all: vmlinux

-ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE

-CFLAGS += -Os

-else

-CFLAGS += -O2

-endif

include $(srctree)/arch/$(ARCH)/Makefile

-ifdef CONFIG_FRAME_POINTER

-CFLAGS += -fno-omit-frame-pointer $(call cc-option,-fno-optimize-sibling-calls,)

-else

-CFLAGS += -fomit-frame-pointer

-endif

ifdef CONFIG_UNWIND_INFO

CFLAGS += -fasynchronous-unwind-tables

endif

-ifdef CONFIG_DEBUG_INFO

-CFLAGS += -g

-endif

+#ifdef CONFIG_DEBUG_INFO

+CFLAGS += -fno-omit-frame-pointer $(call cc-option,-fno-optimize-sibling-calls,)

+CFLAGS += -g -ggdb

+CFLAGS += -O

+#else

+

+# ifdef CONFIG_FRAME_POINTER

+ CFLAGS += -fno-omit-frame-pointer $(call cc-option,-fno-optimize-sibling-calls,)

+# else

+ CFLAGS += -fomit-frame-pointer

+# endif

+

+# ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE

+ CFLAGS += -Os

+# else

+ CFLAGS += -O2

+# endif

+

+#endif

通过以上修改后，系统的的调试信息简单的通过CONFIG_DEBUG_INFO宏来控制了，那么CONFIG_DEBUG_INFO宏又是从哪里来的呢?它其实是从内核的配置文件.config里面来的。

一般内核通过make menuconfig做配置的时候，都有

Kernel hacking --->

[*] Kernel debugging

[*] Compile the kernel with debug info

[*] Force gcc to inline functions marked 'inline' (2.6比较新的内核有这一项)