I want to get kernel source code file name and line number of a kernel function from the function address that ftrace outputed on rapberry pi 3.
I tried addr2line -e /boot/kernel8.img [function address] on raspberry pi 3. But it returned addr2line: /boot/kernel8.img: File format not recognized.
note:
kernel8.img is customed kernel that i compiled. I cloned kernel source from https://github.com/raspberrypi/linux.git, checkouted to rpi-4.18.y, turned on CONFIG_DEBUG_INFO, and run make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j4. This compile work performed on ubuntu x86_64 linux kernel 4.15.0-23-generic. The type of kernel8.img is as follows.
$ file kernel8.img
kernel8.img: MS-DOS executable
thanks
You need to run addr2line against the vmlinux file (i.e. uncompressed/raw kernel binary). /boot/kernel8.img is, most probably, a zImage (i.e. compressed kernel).
You can find the vmlinux file in the root of your kernel sources after compilation.
Related
I need to know the version of a kernel file without running it. Therefore, the following questions arise in this realm:
Is it possible to get the kernel version in the u-boot environment? I mean before running the kernel I want to get the version of my kernel file.
Suppose I am running ubuntu on my amd64 processor and I have a zImage file which is cross compiled for ARM processor. Therefore I can not run this zImage file on amd64. Then how can I get version of this zImage file without running it on an ARM processor? I checked out uname manual but it does not accept a file as argument. I also issued readelf -V on a vmlinux kernel file, but it was an unsuccessful attempt.
How do I extract the kernel configuration from a kernel image file?
The kernel image file type is:
/boot/kernel7.img: Linux kernel ARM boot executable zImage (little-endian)
The kernel has been compiled with CONFIG_IKCONFIG enabled. However,
scripts/extract-ikconfig /boot/kernel7.img
returns
extract-ikconfig: Cannot find kernel config.
Note: I am trying the get the config without booting the kernel.
If the kernel has been compiled with CONFIG_IKCONFIG=m (note the m), the configuration in stored in a module (configs.ko) and not in the kernel itself. That's the reason why running extract-ikconfig on the kernel image fails.
In this case, we can extract the config from the configuration module:
/usr/src/$(uname -r)/scripts/extract-ikconfig \
/lib/modules/$(uname -r)/kernel/kernel/configs.ko
I am compiling Linux Kernel to my ARM board. I have seen file called vmlinux generated in kernel root folder. Can someone give good explanation about this file and it's use.
vmlinux is a ELF format based file which is nothing but the uncompressed version of kernel image which can be used for debugging. The zImage or bzImage are the compressed version of kernel image which is normally used for booting.
The vmlinux as such directly cannot be used by UBoot. However, by addition of metadata info in the process of creation of uImage for vmlinux, it is possible to boot via UBoot.
The vmlinux is the boot file in ELF format, and then the initrd file (ram disk) is run in the same directory (/boot).
The vmlinux file is practically the kernel itself.
I'm currently patching Ext4 for academic purposes (only linux/fs/ext4/*, like file.c, ioctl.c, ext4.h) . I'm working on the QEMU virtual machine, and to speed up the whole process I've selected Ext4 to compile as a kernel module. The problem occurs when it comes to test new changes, as, even though I run make modules ARCH=x86 && make modules_install ARCH=x86 and reboot the machine (/ is Ext4), they are not visible unless I recompile the whole kernel. It's a little bit weird as I have a variety of signs that the Ext4 has been compiled as a module:
It is configured as that:
$ grep EXT4 .config
CONFIG_EXT4_FS=m
It does compile as a module:
$ make modules ARCH=x86
(...)
CC [M] fs/ext4/ioctl.o
LD [M] fs/ext4/ext4.o
Building modules, stage 2.
MODPOST 3 modules
LD [M] fs/ext4/ext4.ko
After $ make modules_install ARCH=x86 the files in /lib/modules/3.13.3/kernel/fs/ have proper time stamp.
Finally:
$ lsmod
Module Size Used by
ext4 340817 1
(...)
For some reason I have to do $ make all ARCH=x86 in order to see my changes appear in the runtime. What have I missed? Thanks!
Most boot processes use an "initial ramdisk" (initrd) which contains all kernel modules which the kernel needs to load to be able to do anything - after all, to read files from an Ext4 file system, the kernel needs a driver for this file system and if the driver is on said file system, well, ...
So the solution is to pack all those files into an archive (the initial ramdisk) and save the hard disk blocks as a list of numbers in the boot loader. It can then use a primitive IDE/SATA driver to load the blocks directly, extract the drivers and load them.
Check the documentation of your linux distro to find out how to update initrd. On my Ubuntu Linux, it's mkinitramfs.
Related:
Linux initial RAM disk (initrd) overview
I'm trying to compile a kernel (altered version of 2.6.32.9, found here https://github.com/rabeeh/linux-2.6.32.9). I am doing the compilation on a emulated ARM system (qemu) (yes, I should probably cross-compile, but that's a different topic) running Ubuntu Core (https://wiki.ubuntu.com/Core) and the kernel (vmlinuz) from Ubuntu 11.04 (downloaded from http://ports.ubuntu.com/ubuntu-ports/dists/natty/main/installer-armel/current/images/versatile/netboot/vmlinuz).
After running make bzImage, I look in the arch/arm/boot folder, and find only a file called zImage. I tried using this zImage instead of the vmlinuz I downloaded from ubuntu.com in qemu, but that doesn't work, just shows a black screen. I guess zImage is not the same as bzImage, which is what I think vmlinuz (judging from different articles on the internet) is.
So, a few questions:
Why doesn't make bzImage produce a bzImage/vmlinuz?
Can I convert a vmlinux to a vmlinuz using for example mkimage (there are lots of guides on the opposite...)?
Thanks
The bzImage filename and make target was originally x86-specific (big zImage). Many of the bootloaders on architectures that are not equal to baremetal-x86 (SPARC, PPC, IA64, etc. and also Xen on *) directly take vmlinux (or one of its compressed forms, for example vmlinux.gz, aka zImage). I guess some maintainers just added bzImage as a make target name because they wanted to have the x86 madness on their arch as well.
I get the result you describe by asking qemu to emulate a different cpu than arm926ej-s. But booting versatilepb with the default cpu works. I've cross-compiled my kernel, and I compiled all the drivers into it (so I don't use initrd).
Just download 100MB arm-eabi toolchain from http://www.mentor.com/embedded-software/sourcery-tools/sourcery-codebench/editions/lite-edition/ (it's free but they want your email, like the x86 Intel compiler). It has an installer, just say "next" until it's done, like on Windows. Then add the bin directory to your path:
export PATH=~/CodeSourcery/Sourcery_CodeBench_Lite_for_ARM_EABI/bin/:$PATH
Then go back to your kernel source dir and do
make ARCH=arm CROSS_COMPILE=arm-none-eabi- menuconfig
make ARCH=arm CROSS_COMPILE=arm-none-eabi- zImage modules
You can do
sudo make ARCH=arm CROSS_COMPILE=arm-none-eabi- INSTALL_MOD_PATH=path_to_arm_root modules_install
if you can reach your ARM filesystem from the host. If you're using NFS root it's trivial, but if you're using a disk image you need to either:
use a raw disk image and kpartx (depends on your host kernel having dm-multipath) or
qemu-nbd which supports qcow (and depends on host kernel having network block device support)
To boot in qemu with disk you need the right drivers (SYM53C8XX SCSI). The versatile defconfig doesn't select those.