Re: [Qemu-devel] Debugging aarch64 guest running on Foundationv8 model

[Xuebing wang]

Hi Jani,

The video is about aarch64 (not 32-bit arm).

For your original issue, I think you need armv8 MMU support (which is not merged yet), so qemu can not handle guest virtual address like 0xffffffc000636498.

I just tried Peter's branch, using aarch64-qemu + aarch64-gdb to cross-debug arm64-kernel is working here.
-- But, because aarch64 timer is not implemented in the current qemu, thus I can not get arm64-kernel scheduler working.

Peter's branch is here:
git://git.linaro.org/people/pmaydell/qemu-arm.git
branch: a64-system

Command I am using:
1) in one terminal:
./aarch64-softmmu/qemu-system-aarch64  -kernel ../../kernel/arch/arm64/boot/Image  -machine virt -cpu cortex-a57 -s -S

2) in another terminal
aarch64-linux-gnu-gdb  ../../kernel/vmlinux
target remote tcp::1234
b start_kernel

On 02/27/2014 11:35 PM, Jani Kokkonen wrote:

Hi Xuebing,

In that video the qemu seems use 32-bit ARM cpu model whereas I have need to use 64-bit ARM cpu model as I have specified by "-cpu host" qemu parameter in Foundationv8 model.

-Jani

2014-02-27 14:21 GMT+01:00 Xuebing wang <address@hidden>:

Hi Jani,

Is below video similar to what you want? This video shows cross-debug armv8 linux kernel (using armv8-gdb + armv8-qemu).

http://www.youtube.com/watch?v=MLu5EzheHIM

On 02/27/2014 05:52 PM, Peter Maydell wrote:

On 27 February 2014 09:45, Jani Kokkonen <address@hidden> wrote:

Hi,

I would like to debug a Qemu guest linux kernel under Foundationv8 model and
I tried  the following setup:

1.  Foundationv8 model started with --network=nat and
--network-nat-ports=1234=1234 options
2. In Foundationv8 model I started qemu-system-aarch64 with the command
line:

./qemu-system-aarch64  -M virt -cpu host  -kernel Image -serial stdio
-display none  -enable-kvm -gdb tcp::1234 -S

3. I start debugging the guest kernel with aarch64-linux-gnu-gdb vmlinux
and with target remote:1234 command.

However when I set any breakpoint I will get error message:
"Cannot insert breakpoint 1.
Error accessing memory address 0xffffffc000636498: Unknown error -1"
In addition stepi or any other run related command does not work.

You would need to implement breakpoint support for AArch64 in
both KVM and QEMU, I think. That feature is currently not implemented.

thanks
-- PMM

--
Thanks,
Xuebing Wang

-- 
Thanks,
Xuebing Wang