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

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

[Jani Kokkonen]

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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.

Any ideas to fix this?

-Jani

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

[Peter Maydell]

On 27 February 2014 09:45, Jani Kokkonen <janimikokkonen@gmail.com> 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

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

[Xuebing wang]

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 <janimikokkonen@gmail.com> 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

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

[Jani Kokkonen]

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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 <xbing6@gmail.com>:

> 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 <janimikokkonen@gmail.com>
>> 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
>
>

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

[Xuebing wang]

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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 <xbing6@gmail.com 
> <mailto:xbing6@gmail.com>>:
>
>     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
>         <janimikokkonen@gmail.com <mailto:janimikokkonen@gmail.com>>
>         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


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