Linux kernel development under emulator

[Chris Furlough]

Hey Guys.

I'm trying to do some custom kernel development under the goldfish emulator.  I've compiled my own kernel (using the goldfish config), and gdb.  I'm having some problems that I hope you guys can help with.  (I've exhausted my google searches and online tutorials).

I'm using Android Studio to launch the emulator with the following command line:

/home/android/Android/Sdk/tools/emulator -avd Nexus_10_API_19 -netspeed full -netdelay none -show-kernel -qemu -s -S -kernel /home/android/goldfish/arch/arm/boot/zImage

This loads, and stops as you'd expect.  I launch gdb in a different window:

~/WholeTree/prebuilts/gcc/linux-x86/arm/arm-eabi-4.7/bin$ ./arm-eabi-gdb ~/goldfish/vmlinux

I then do this:

(gdb) target remote :1234

Remote debugging using :1234

0x00000000 in ?? ()

Obviously that 0x00000000 is a problem.  The kernel versions match.  Why is this?

I'm working with the early boot stuff inside the Linux kernel.  

When I launch the kernel, via:

(gdb) cont

Continuing.

I get this:

serial0 console

Uncompressing Linux... done, booting the kernel.

And then it hangs.  

When I ctrl-c it, I get:

^C

Program received signal SIGINT, Interrupt.

0x0044f82c in ?? ()

I'm not asking for help with my CODE, only my debugging.  Any ideas what my GDB problem is here?

[Emeric VIGIER]

Try enabling EARLY_PRINTK for your platform. This may or not may not be supported. If it is, add the proper command line argument to enable this, visit those:

http://smackerelofopinion.blogspot.ca/2009/11/kernel-early-printk-messages.html?m=1

http://elinux.org/Debugging_by_printing#Debugging_early_boot_problems

What version of Linux did you compile? What toolchain did you use?

Emeric

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[karthik poduval]

I have done this earlier directly with qemu-kvm. 

I used to launch the QEMU with the  commandline:-

qemu-kvm -hda MyImage.raw -m 128 -redir tcp:12345::22 -nographic -s -S

and then gdb using

$ gdb <path-to-vmlinux>

target remote:1234

Not sure if this is useful to you, but the above combination worked for me.

Is the same gcc cross compiler (arm-eabi-gdb) being used to build the kernel ?

--

Regards,

Karthik Poduval

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Regards,
Karthik Poduval

[Ye Roger]

There are a lot of articles about this. You can do a google search of "Embedded Android".