[Open SoC Debug] CDM: Next Steps

SHIVAM AGGARWAL shivam16195 at iiitd.ac.in
Wed Jul 18 12:33:17 CEST 2018


Hi

I have completed the implementation of following commands in the GDBserver.

`g'                                   --   read general-purpose registers
`G'XX...                           --   write general-purpose register
`p n'                                --   Read the value of register n
`P n...=r...'                    --   Write register n... with value r
`m'ADDR`,'LENGTH         --   read memory
`M'ADDR,LENGTH`:'XX... --   write memory

I have added unit tests to check the functionality of intermediate
functions like encodeRSPpacket, etc.

What's Next?
I am trying to implement a *mock_gdbclient program* to test various
functionality of GDBserver. I am not thoroughly clear with the
implementation details of the mock_gdbclient program. I went through the
implementation of both mock_hostmod and mock_hostcontroller.
Based on my understanding and previous discussions, some utilities of the
mock_gdbclient program:

1. It should be able to connect to the GDBserver via TCP.

For this part, I think I need to use functions from the *PThreads API *with
one thread running GDBserver. We need to run the client and the server part
simultaneously and hence, multithreading.

2. The program should respond to the queries/requests made by the
GDBserver. This part of the program essentially depends upon the connection
with the GDBserver.

It would be great if you could elaborate a bit on the specific details of
the establishing a TCP connection.

Thanks

*Shivam Aggarwal*
Coordinator | Electroholics
Event Head | Circuitrix Jr., Esya'18
ECE BTech'16

Okhla Industrial Estate,Phase III
New Delhi, India - 110020

On Thu, Jun 28, 2018 at 2:22 AM, SHIVAM AGGARWAL <shivam16195 at iiitd.ac.in>
wrote:

> Hi,
>
> I have worked on the following features of the OSD-GDB server:
> 1. Connection with GDB over TCP.
> 2. Send/Receive data to the client.
> 3. Send/Receive packet-data from the obtained buffer
> ($packet-data#checksum)
> 4. Validate the packet-data using checksum
>
> I have opened a PR and will keep updating it with the rest of the features.
>
> Associated PR:
> https://github.com/opensocdebug/osd-sw/pull/20
>
> I tested these features with GDB by compiling the code completely
> independent of
> the OSD framework. As a workaround, I used the below code for testing.
> https://github.com/shivmgg/osd-sw/blob/gdbserver/src/
> libosd/osd_gdbserver.c
> All the features are working successfully.
>
> Is it possible to test the gdbserver using unit-tests (for example,
> something like
> checkpacket.c)?
>
> Next steps:
> 1. To implement following use-cases/commands of the RSP protocol:
>
> `?'                                  --   last signal
> `g'                                  --   read registers
> `G'XX...                          --   write regs
> `m'ADDR`,'LENGTH         --   read memory
> `M'ADDR,LENGTH`:'XX... --   write mem
> 'c'                                    --  continue
> `z'TYPE`,'ADDR`,'LENGTH -- remove breakpoint or watchpoint (only, SW
> breakpoint (for now))
> `Z'TYPE`,'ADDR`,'LENGTH -- insert breakpoint or watchpoint (only SW
> breakpoint (for now))
> 's'                                     --  step (optional)
>
> 2. To implement signal-handling. As per my understanding, we only need
> SIGINT
> and SIGTRAP (for minimum support) to set software breakpoints, etc.
> Please provide some insight for this part.
>
> Thanks
> *Shivam Aggarwal*
>
> On Sun, Jun 24, 2018 at 12:37 AM, Philipp Wagner <philipp.wagner at tum.de>
> wrote:
>
>> Am 23.06.2018 um 20:08 schrieb SHIVAM AGGARWAL:
>> > I believe I can first ensure the complete implementation of GDBserver on
>> > GDB side.
>> > Please see below for details.
>>
>> Yes, sounds like a plan.
>>
>> > So, as per my understanding, I should keep the things simple and smooth
>> > in the
>> > beginning. This would ensure a rough yet working solution in hand. As
>> > per your
>> > proposed implementation details, I believe we can divide the code as
>> below:
>> >
>> > osd_gdbserver.c: This file should contain all the API covering
>> > connection(),
>> > set_breakpoint(), get_breakpoint(), fetch_data(), RSP specific
>> > functions, etc.
>> > Also, I should making a or1k specific file and keep the things minimal.
>>
>> That sounds roughly right, but we need to discuss that based on the code
>> itself once it's there.
>>
>> Philipp
>>
>
>
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