Insight / ARM-Thumb question

Insight / ARM-Thumb question

[Dave Bryan]

Hi,

I'm running Insight 6.4 for Arm-elf on Windows XP using Cygwin. The target  
is a Philips ARM LPC2214 run via a remote GDB server.

I'm able to download, step & run programs compiled for ARM on the target.  
When I compile one or more files for Thumb (mixed ARM & Thumb code) I'm  
still able to download & run programs. However, whenever I try to step  
into a function compiled for Thumb (from ARM code) I don't actually step  
through each line in that function, instead it is as though I've selected  
step-over rather than step-into the function.

I've tried two different types of remote GDB server (same target) & both  
do the same thing so I don't think there's an issue there. I've set infrun  
to 1 in the GDB console window & included the output resulting from  
stepping 'into' a Thumb function below:

infrun: proceed (addr=0xffffffff, signal=144, step=1)
infrun: resume (step=1, signal=0)
infrun: wait_for_inferior
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x81004d2c
infrun: stepped into subroutine
infrun: resume (step=0, signal=0)
infrun: prepare_to_wait
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x81001c2c
infrun: BPSTATE_WHAT_STEP_RESUME
infrun: stepped to a different line
infrun: stop_stepping

(gdb)

Is being unable to step into a Thumb function a known bug in the Arm-Elf  
version of Insight/GDB ?

Thanks
Dave Bryan

Re: Insight / ARM-Thumb question

[Keith Seitz]

Dave Bryan wrote:
> 
> [...] However, whenever I try
> to step into a function compiled for Thumb (from ARM code) I don't 
> actually step through each line in that function, instead it is as 
> though I've selected step-over rather than step-into the function.

I have to ask: are you sure there is debug info for the function into 
which you are stepping? Open a console and type "info func 
THUMB_FUNCTION". [Or use the function browser from the Window menu.]

This behavior is expected with GDB when the user attempts to step into a 
function for which there is no debug info. GDB steps over it.

> Is being unable to step into a Thumb function a known bug in the Arm-Elf 
> version of Insight/GDB ?

I haven't read anything about it. Your best bet is to use command line 
gdb to reproduce the problem, saving the output of the entire session to 
a file. Then send this transcript to the folks on the gdb mailing list. 
They'll be able to help you much more than I can.

BTW, have you tried a recent snapshot? That might prove useful. [I'm 
sure this will be the first thing GDB people ask! :-)]

Keith