gdb remote serial protocol qC and vCont question

gdb remote serial protocol qC and vCont question

[Kishore Paul]

Hi,

Is there a way to communicate thread switching using a reply packet in 
gdb's remote serial protocol.

I notice the qC packet sent only at the begining and so later when a 
thread switch happens in the target a vCont packet is sent with the old 
active thread Id.

Thanks,
Kishore

Re: gdb remote serial protocol qC and vCont question

[Daniel Jacobowitz]

On Thu, Dec 07, 2006 at 06:27:25PM -0600, Kishore Paul wrote:
> Hi,
> 
> Is there a way to communicate thread switching using a reply packet in 
> gdb's remote serial protocol.
> 
> I notice the qC packet sent only at the begining and so later when a 
> thread switch happens in the target a vCont packet is sent with the old 
> active thread Id.

GDB is supposed to send vCont for the correct thread; if it doesn't,
something's wrong on the GDB side.

-- 
Daniel Jacobowitz
CodeSourcery

Re: gdb remote serial protocol qC and vCont question

[Daniel Jacobowitz]

On Thu, Dec 07, 2006 at 08:29:11PM -0600, Kishore Paul wrote:
> Received packet: [vCont;s:1;c]  -------------> (1)
> ....
>  < thread switch happens to 2 >
> ....
> <receives S05>
> Received packet: [vCont;s:1;c]  -------------> (2)*
> 
> 
> Between the first and second vCont packet the thread-id changes from 1 
> to 2 but this information is somehow not getting communicated to gdb. 
> The intent of the second vCont is to do a step for thread 2 and c for 
> all other threads.

How do you expect GDB to know this if you aren't telling it?  It can't
guess!

The thing you're missing is the 'T' response and the "thread:" item in
it.

-- 
Daniel Jacobowitz
CodeSourcery

Re: gdb remote serial protocol qC and vCont question

[Kishore Paul]

Daniel,

The T packet works and I am seeing the threads switching now.

Thanks,
Kishore

Daniel Jacobowitz wrote:

>On Thu, Dec 07, 2006 at 08:29:11PM -0600, Kishore Paul wrote:
>  
>
>>Received packet: [vCont;s:1;c]  -------------> (1)
>>....
>> < thread switch happens to 2 >
>>....
>><receives S05>
>>Received packet: [vCont;s:1;c]  -------------> (2)*
>>
>>
>>Between the first and second vCont packet the thread-id changes from 1 
>>to 2 but this information is somehow not getting communicated to gdb. 
>>The intent of the second vCont is to do a step for thread 2 and c for 
>>all other threads.
>>    
>>
>
>How do you expect GDB to know this if you aren't telling it?  It can't
>guess!
>
>The thing you're missing is the 'T' response and the "thread:" item in
>it.
>
>  
>

Re: gdb remote serial protocol qC and vCont question

[Kishore Paul]

Daniel,

I am using an RSP stub (like gdbserver)  built with  our ISS model so I 
am not sure whether I am providing the right information to gdb for  the 
thread switching.

The RSP transactions look something like:

Received packet: [qC]
Sending packet:  [QC1]
Received packet: [qfThreadInfo]
Sending packet:  [m1,2,3]
Received packet: [qsThreadInfo]
Sending packet:  [l]
....
Received packet: [vCont;s:1;c]  -------------> (1)
....
  < thread switch happens to 2 >
....
 <receives S05>
Received packet: [vCont;s:1;c]  -------------> (2)


Between the first and second vCont packet the thread-id changes from 1 
to 2 but this information is somehow not getting communicated to gdb. 
The intent of the second vCont is to do a step for thread 2 and c for 
all other threads.


Really appreciate your help.

Thanks,
Kishore


Daniel Jacobowitz wrote:

 >On Thu, Dec 07, 2006 at 06:27:25PM -0600, Kishore Paul wrote:
 > 
 >
 >>Hi,
 >>
 >>Is there a way to communicate thread switching using a reply packet in
 >>gdb's remote serial protocol.
 >>
 >>I notice the qC packet sent only at the begining and so later when a
 >>thread switch happens in the target a vCont packet is sent with the old
 >>active thread Id.
 >>   
 >>
 >
 >GDB is supposed to send vCont for the correct thread; if it doesn't,
 >something's wrong on the GDB side.
 >
 > 
 >