porting gdbserver

porting gdbserver

[William Tambe]

Is there an easy to follow documentation or commit that shows how to port
gdbserver for baremetal ?

Re: porting gdbserver

[Luis Machado]

Hi,

On 10/15/20 1:34 PM, William Tambe via Gdb wrote:
> Is there an easy to follow documentation or commit that shows how to port
> gdbserver for baremetal ?
> 

I'm afraid there isn't. I suppose you are talking about actually coming 
up with a debugging stub that implements the most minimal set of remote 
protocol packets, right? Not "gdbserver" itself, which is always OS-hosted.

 From the documentation here...

https://sourceware.org/gdb/onlinedocs/gdb/Overview.html#Overview

... it says:

"At a minimum, a stub is required to support the ‘?’ command to tell GDB 
the reason for halting, ‘g’ and ‘G’ commands for register access, and 
the ‘m’ and ‘M’ commands for memory access. Stubs that only control 
single-threaded targets can implement run control with the ‘c’ 
(continue) command, and if the target architecture supports 
hardware-assisted single-stepping, the ‘s’ (step) command. Stubs that 
support multi-threading targets should support the ‘vCont’ command. All 
other commands are optional."

But the above may be stale at this point.

Re: porting gdbserver

[Christo Crause]

On Thu, 15 Oct 2020, 20:24 Luis Machado via Gdb, <gdb@sourceware.org> wrote:

> Hi,
>
> On 10/15/20 1:34 PM, William Tambe via Gdb wrote:
> > Is there an easy to follow documentation or commit that shows how to port
> > gdbserver for baremetal ?
> >
>
> I'm afraid there isn't. I suppose you are talking about actually coming
> up with a debugging stub that implements the most minimal set of remote
> protocol packets, right? Not "gdbserver" itself, which is always OS-hosted.


An example of a bare metal stub on an 8 bit AVR:
https://github.com/jdolinay/avr_debug

The remote protocol handling is implemented here
https://github.com/jdolinay/avr_debug/blob/master/avr8-stub/avr8-stub.c