Powerpc構架系統內核和內核模塊調試

說明：

此文檔的目標系統為freescale MPC8349E-mITX,對其他采用powerPC,MIPS，ARM的芯片的系統亦具有參考意義。 此文檔中內核調試為了簡化，采用目標系統中的UBOOT初始化目標板，并通過UBOOT或者BDI2000加載內核到目標板的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要改為主機IP，關鍵的字段MMU XLAT 和PTBASE 是POWERPC和MIPS經常需要設置的，關于PTBASE的具體設置，超出本文范圍，詳細情況請參考BDI2000的手冊

2.內核修改和配置

為了能夠調試內核，需要在內核中的Makefile中增加如下調試選項：

CFLAGS 增加C代碼調試選項-g –ggdb

AFLAGS 增加匯編代碼調試選項：-Wa,-L -gdwarf-2

去掉CFLAGS編譯選項中-fomit-frAME-pointer

GCC的-fomit-frame-pointer選項是優化函數棧回溯(stack backtrace)的，我們調試的時候需要提供函數回溯能力，所以我們要去掉這個選項，當然，有的系統系統不受它的影響，或者說它不起作用，為了統一，我們統一去掉它。

相對個案來說，我是做如下改動的：

--- 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

通過以上修改后，系統的的調試信息簡單的通過CONFIG_DEBUG_INFO宏來控制了，那么CONFIG_DEBUG_INFO宏又是從哪里來的呢?它其實是從內核的配置文件.config里面來的。

一般內核通過make menuconfig做配置的時候，都有

Kernel hacking --->

[*] Kernel debugging

[*] Compile the kernel with debug info

[*] Force gcc to inline functions marked 'inline' (2.6比較新的內核有這一項)