Question

I want to extract kernel symbols from a u-boot image

The final goal is to debug syscalls with gdb

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The kernel is compiled with CONFIG_DEBUG_INFO=y and gcc is using -g option (I checked)

After make uImage, I’ve :

# file arch/arm/boot/*
arch/arm/boot/bootp:           directory
arch/arm/boot/compressed:      directory
arch/arm/boot/Image:           data
arch/arm/boot/install.sh:      POSIX shell script text executable
arch/arm/boot/Makefile:        ASCII English text
arch/arm/boot/uImage:          u-boot legacy uImage, Linux-3.0.6, Linux/ARM, OS Kernel Image (Not compressed), 3044476 bytes, Thu Mar 22 18:13:40 2012, Load Address: 0x00008000, Entry Point: 0x00008000, Header CRC: 0xF689B805, Data CRC: 0x6BFE76DF
arch/arm/boot/zImage:          data

gdb cannot load uImage directly

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I tried this script http://forum.xda-developers.com/showthread.php?t=901152.

# file arch/arm/boot/zImage_unpacked/*
arch/arm/boot/zImage_unpacked/decompression_code:     data
arch/arm/boot/zImage_unpacked/initramfs.cpio+part3:   data
arch/arm/boot/zImage_unpacked/kernel.img:             data
arch/arm/boot/zImage_unpacked/padding_piggy:          data
arch/arm/boot/zImage_unpacked/piggy:                  data
arch/arm/boot/zImage_unpacked/piggy.gz:               gzip compressed data, from Unix, max compression
arch/arm/boot/zImage_unpacked/piggy.gz+piggy_trailer: gzip compressed data, from Unix, max compression
arch/arm/boot/zImage_unpacked/piggy_trailer:          data
arch/arm/boot/zImage_unpacked/sizes:                  ASCII text

kernel.img is not loadable by gdb

Answer 1

Do make vmlinux. I believe GDB can read that, but it’s a long time and a lot of kernel versions since I tried.

EDIT: Oh, I should say, both vmlinux and uImage should be the same but packaged differently. If that’s not the case, then this won’t work.