Re: Reset breakpoint after load?

[Jie Zhang <jie.zhang@analog.com>]

On 01/22/2010 05:19 AM, Daniel Jacobowitz wrote:
> On Thu, Jan 21, 2010 at 10:29:06AM -0800, Michael Snyder wrote:
>>> On 19/01/2010 07:36, Jie Zhang wrote:
>>>
>>>> gdb-comm.exp sets breakpoints on exit and abort before load. The problem
>>>> is that GDB tries to skip prologue according to what it reads from
>>>> memory, which might contain random data since the executable has not
>>>> been loaded into memory. In my case, sometimes skip_prologue might skip
>>>> one or two more instructions, which happens to be an exception
>>>> instruction and will trap the processor into an exception event loop
>>>> after running the executable before hit the breakpoints.
>
> I've had this problem on a MIPS target, too.
>
I didn't notice this issue until recently a bug in toolchain linked in 
simulator libc for bare metal executable, which made this issue easily 
happen.

>> I don't believe that gdb can tell when the (remote) inferior
>> is started.  All gdb knows is that target remote is started.
>> Thus, if we connect to target remote and then load the image,
>> there is an interval during which gdb will attempt to read
>> the prologue bytes from un-initialized target memory.
>>
>> Seems to me, that interval is a bad time to set breakpoints.
>
> The problem isn't just breakpoints set during the interval, but also before
> target remote.  We adjust the breakpoints after target remote.
>
> GDB doesn't know whether we're going to need to load.  Maybe it should
> be an option to target remote to load automatically?  I don't know,
> that's a little strange.
>
Yeah, it's a little strange.


Jie