[ECOS] GDB stub support

[ECOS] GDB stub support

[Bernd Schuster]

Hi, 

unfortunately I couldn`t get GDB working as expected. 

At the moment, I`m able to run Redboot at my target system - mips32 24kc processor as ROMRAM version. When redboot starts, I`m able to see all messages from the redboot bootloader by my serial port ttyS0 (configurated with 115200 baud). After that redboot starts my application which is located at the addr 0x800400BC by a short boot script. 

Now, I`m trying to add GDB support by using the same serial interface ttyS0. I`m not totally sure if that could be already the problem, because my application also puts some messages to this serial interface. 

When I enable GDB with the following commands I can see that cutecom - terminal programm - will go from the open to the close state. That`s seems a correct behaviour to me. Furthermore I got a very small message on the serial terminal - something like that: 

RedBoot> 
RedBoot>+$#00

Here are the steps from the console: 

xxxxx@xxxxx:~/../build/obj> mipsisa32-elf-gdb myProgramm.elf
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu --target=mipsisa32-elf"...
(gdb) set remotebaud 115200
(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
Ignoring packet error, continuing...
warning: unrecognized item "timeout" in "qSupported" response
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Ignoring packet error, continuing...

I hope anyone of you have some hints / information solving the problem. 

best regards
Bernd



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[ECOS] Re: GDB stub support

[John Dallaway]

Hi Bernd

On 17/12/12 17:24, Bernd Schuster wrote:

> unfortunately I couldn`t get GDB working as expected. 
> 
> At the moment, I`m able to run Redboot at my target system - mips32
> 24kc processor as ROMRAM version. When redboot starts, I`m able to
> see all messages from the redboot bootloader by my serial port ttyS0
> (configurated with 115200 baud). After that redboot starts my
> application which is located at the addr 0x800400BC by a short boot
> script. 
> 
> Now, I`m trying to add GDB support by using the same serial interface
> ttyS0. I`m not totally sure if that could be already the problem,
> because my application also puts some messages to this serial interface. 
> 
> When I enable GDB with the following commands I can see that cutecom -
> terminal programm - will go from the open to the close state. That`s
> seems a correct behaviour to me. Furthermore I got a very small message
> on the serial terminal - something like that: 
> 
> RedBoot> 
> RedBoot>+$#00

You have two host-side applications competing for incoming characters
arriving on a single serial port. In the above example, your terminal
emulator has received characters intended for GDB. You must close your
terminal program before attempting to connect to RedBoot's GDB stub.

It is perfectly feasible to use a single channel for both debug and
diagnostics as you suggest. You should configure eCos (for your
application build) with CYG_HAL_STARTUP == "RAM" and with
CYGSEM_HAL_USE_ROM_MONITOR enabled. You should then find that (by
default) diagnostic/trace messages from your application are routed via
the GDB stub and appear within your GDB session on the host.

For avoidance of doubt, you can use the GDB "load" command to download
your application to RAM when debugging an application configured for RAM
startup. It is not necessary to load it at the "RedBoot>" prompt.

I hope this helps...

John Dallaway
eCos maintainer
http://www.dallaway.org.uk/john

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Re: [ECOS] Re: GDB stub support

[Bernd Schuster]

Hi John, 

-------- Original-Nachricht --------
> Datum: Mon, 17 Dec 2012 19:00:50 +0000
> Von: John Dallaway <john@dallaway.org.uk>
> An: schuster_bernd@gmx.net
> CC: eCos Discussion <ecos-discuss@ecos.sourceware.org>
> Betreff: [ECOS] Re: GDB stub support

> Hi Bernd
> 
> On 17/12/12 17:24, Bernd Schuster wrote:
> 
> > unfortunately I couldn`t get GDB working as expected. 
> > 
> > At the moment, I`m able to run Redboot at my target system - mips32
> > 24kc processor as ROMRAM version. When redboot starts, I`m able to
> > see all messages from the redboot bootloader by my serial port ttyS0
> > (configurated with 115200 baud). After that redboot starts my
> > application which is located at the addr 0x800400BC by a short boot
> > script. 
> > 
> > Now, I`m trying to add GDB support by using the same serial interface
> > ttyS0. I`m not totally sure if that could be already the problem,
> > because my application also puts some messages to this serial interface.
> > 
> > When I enable GDB with the following commands I can see that cutecom -
> > terminal programm - will go from the open to the close state. That`s
> > seems a correct behaviour to me. Furthermore I got a very small message
> > on the serial terminal - something like that: 
> > 
> > RedBoot> 
> > RedBoot>+$#00
> 
> You have two host-side applications competing for incoming characters
> arriving on a single serial port. In the above example, your terminal
> emulator has received characters intended for GDB. You must close your
> terminal program before attempting to connect to RedBoot's GDB stub.
> 
> It is perfectly feasible to use a single channel for both debug and
> diagnostics as you suggest. You should configure eCos (for your
> application build) with CYG_HAL_STARTUP == "RAM" and with
> CYGSEM_HAL_USE_ROM_MONITOR enabled. You should then find that (by
> default) diagnostic/trace messages from your application are routed via
> the GDB stub and appear within your GDB session on the host.

That means, it is much more comfortable to download only the redboot bootloader to my flash memory and download the application (eCos O/S together with my own software app) by GDB instead of having already everything installed on my MIPS board? I asked this because it will take some time to download the application by serial port instead of being able to download a new file by ethernet. 

I already found the specific ecm file where 
cdl_component CYG_HAL_STARTUP {
    user_value ROMRAM
};
I have to specify RAM instead of ROMRAM. It seams that CYGSEM_HAL_USE_ROM_MONITOR is already enabled if I use RAM instead of ROMRAM. 


> For avoidance of doubt, you can use the GDB "load" command to download
> your application to RAM when debugging an application configured for RAM
> startup. It is not necessary to load it at the "RedBoot>" prompt.

Do I have to specify the correct RAM-addr where the application has to be downloaded? Because the load command consists only of "load filename".  
 
> I hope this helps...

Thanks for your help in advance!

best regards
Bernd

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Re: [ECOS] Re: GDB stub support

[Bernd Schuster]

Hi, 

ok I got the first step working. I`m able to download the .elf file by the serial connection to my target. 

But could you tell me how I could set some breakpoints at function "web_init" or at line 233 (file web.c). 

xxx@linux-xxxx:~/.../build> mipsisa32-elf-gdb
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu --target=mipsisa32-elf".
(gdb) set remotebaud 115200
(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
0x4cc40080 in ?? ()
(gdb) load obj/myprogramm.elf
Loading section .rom_vectors, size 0xcc lma 0x80040000
Loading section .rel.dyn, size 0x6c0 lma 0x800400cc
Loading section .text, size 0x313eac lma 0x8004078c
Loading section .rodata, size 0xab630 lma 0x80354638
Loading section .data, size 0xf3828 lma 0x803ffc68
Loading section .ctors, size 0x68 lma 0x804f3490
Loading section .dtors, size 0x44 lma 0x804f34f8
Loading section .devtab, size 0x792c lma 0x804f353c
Start address 0x800400bc, load size 4959848
Transfer rate: 10 KB/sec, 666 bytes/write.
(gdb) break obj/web
No symbol table is loaded.  Use the "file" command.
(gdb) break obj/web.o
Can't find member of namespace, class, struct, or union named "obj/web.o"
Hint: try 'obj/web.o<TAB> or 'obj/web.o<ESC-?>
(Note leading single quote.)
(gdb) 

I also tried: 
(gdb) break web_init
No symbol table is loaded.  Use the "file" command.

Using the file command didn`t solve the problem, because it seems to me that GDB didn`t recognize "myprogramm.elf" any more - only the specific file. 

best regards
Bernd 



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Re: [ECOS] Re: GDB stub support

[Bernd Schuster]

oh I just forgot to show us the output using the file command in GDB: 

(gdb) file obj/web.o
Reading symbols from /../build/obj/web.o...done.
(gdb) break web_init
Breakpoint 1 at 0x3490: file ../../.../web.c, line 231.
(gdb) run
Starting program: /.../build/obj/web.o 
Don't know how to run.  Try "help target".
(gdb)

I also get this message, if I don`t use any breakpoint conditions. So maybe the file command is correct to set breakpoints but I need some additional information to get the target running






-------- Original-Nachricht --------
> Datum: Tue, 18 Dec 2012 09:39:18 +0100
> Von: "Bernd Schuster" <schuster_bernd@gmx.net>
> An: "Bernd Schuster" <schuster_bernd@gmx.net>
> CC: ecos-discuss@ecos.sourceware.org
> Betreff: Re: [ECOS] Re: GDB stub support

> Hi, 
> 
> ok I got the first step working. I`m able to download the .elf file by the
> serial connection to my target. 
> 
> But could you tell me how I could set some breakpoints at function
> "web_init" or at line 233 (file web.c). 
> 
> xxx@linux-xxxx:~/.../build> mipsisa32-elf-gdb
> GNU gdb 6.8
> Copyright (C) 2008 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "--host=i686-pc-linux-gnu
> --target=mipsisa32-elf".
> (gdb) set remotebaud 115200
> (gdb) target remote /dev/ttyS0
> Remote debugging using /dev/ttyS0
> 0x4cc40080 in ?? ()
> (gdb) load obj/myprogramm.elf
> Loading section .rom_vectors, size 0xcc lma 0x80040000
> Loading section .rel.dyn, size 0x6c0 lma 0x800400cc
> Loading section .text, size 0x313eac lma 0x8004078c
> Loading section .rodata, size 0xab630 lma 0x80354638
> Loading section .data, size 0xf3828 lma 0x803ffc68
> Loading section .ctors, size 0x68 lma 0x804f3490
> Loading section .dtors, size 0x44 lma 0x804f34f8
> Loading section .devtab, size 0x792c lma 0x804f353c
> Start address 0x800400bc, load size 4959848
> Transfer rate: 10 KB/sec, 666 bytes/write.
> (gdb) break obj/web
> No symbol table is loaded.  Use the "file" command.
> (gdb) break obj/web.o
> Can't find member of namespace, class, struct, or union named "obj/web.o"
> Hint: try 'obj/web.o<TAB> or 'obj/web.o<ESC-?>
> (Note leading single quote.)
> (gdb) 
> 
> I also tried: 
> (gdb) break web_init
> No symbol table is loaded.  Use the "file" command.
> 
> Using the file command didn`t solve the problem, because it seems to me
> that GDB didn`t recognize "myprogramm.elf" any more - only the specific file.
> 
> best regards
> Bernd 
> 
> 
> 
> -- 
> Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
> and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
> 

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[ECOS] Re: GDB stub support

[John Dallaway]

Bernd

On 17/12/12 21:04, Bernd Schuster wrote:

>> It is perfectly feasible to use a single channel for both debug and
>> diagnostics as you suggest. You should configure eCos (for your
>> application build) with CYG_HAL_STARTUP == "RAM" and with
>> CYGSEM_HAL_USE_ROM_MONITOR enabled. You should then find that (by
>> default) diagnostic/trace messages from your application are routed via
>> the GDB stub and appear within your GDB session on the host.
> 
> That means, it is much more comfortable to download only the redboot
> bootloader to my flash memory and download the application (eCos O/S
> together with my own software app) by GDB instead of having already
> everything installed on my MIPS board? I asked this because it will
> take some time to download the application by serial port instead of
> being able to download a new file by ethernet. 

If you have ethernet support built into RedBoot you should also be able
to connect to the GDB stub via TCP for faster download. The default port
number is 9000, so the GDB command would be:

  target remote <target IP address>:9000

> I already found the specific ecm file where 
> cdl_component CYG_HAL_STARTUP {
>     user_value ROMRAM
> };
> I have to specify RAM instead of ROMRAM. It seams that
> CYGSEM_HAL_USE_ROM_MONITOR is already enabled if I use RAM instead of
> ROMRAM. 

That makes sense.

>> For avoidance of doubt, you can use the GDB "load" command to download
>> your application to RAM when debugging an application configured for RAM
>> startup. It is not necessary to load it at the "RedBoot>" prompt.
> 
> Do I have to specify the correct RAM-addr where the application has to be
> downloaded? Because the load command consists only of "load filename".

If you specify the ELF executable filename when you launch GDB then
symbols will be loaded automatically. You can just use "load" with no
filename and "continue" to start execution. The section records in the
elf file will indicate where each section must be loaded. You do not
need to specify the addresses manually.

  bash$ mipsisa32-elf-gdb myProgram.elf
  (gdb) target remote <your parameters>
  (gdb) load
  (gdb) break web_init
  (gdb) continue

I hope this helps...

John Dallaway
eCos maintainer
http://www.dallaway.org.uk/john

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Re: [ECOS] Re: GDB stub support

[Bernd Schuster]

Hi John, 

> If you specify the ELF executable filename when you launch GDB then
> symbols will be loaded automatically. You can just use "load" with no
> filename and "continue" to start execution. The section records in the
> elf file will indicate where each section must be loaded. You do not
> need to specify the addresses manually.
>

Thank you for your help. Could you tell me the reason why the symbol table won`t be loaded or usable starting GDB without specifying a executable? I can`t see the difference. 
 
>   bash$ mipsisa32-elf-gdb myProgram.elf
>   (gdb) target remote <your parameters>
>   (gdb) load
>   (gdb) break web_init
>   (gdb) continue
> 
> I hope this helps...

Yes it helps a lot. I`m now able to set a breakpoint to a specific function like "web_init" without any error message. 

(gdb) break web_init
Breakpoint 1 at 0x80202054: file ../../.../web.c, line 231.
Warning: the current language does not match this frame.
(gdb) break web.c:1549
No line 1549 in file "../../.../web.c".

Viewing the web.c file by Kwrite, the file will have more than 1549 lines of code. For example, the function "web_init" starts at line 1509 instead of line 231 (recognized by GDB). Could you tell me where the difference will come from and if there`s a trick to specify a breakpoint at the correct line number? 


(gdb) set remotebaud 115200
(gdb) target remote /dev/ttyS0
Remote debugging using /dev/ttyS0
0x8000c44c in ?? ()
(gdb) load
Loading section .rom_vectors, size 0xcc lma 0x80040000
Loading section .rel.dyn, size 0x6c0 lma 0x800400cc
Loading section .text, size 0x313eac lma 0x8004078c
Loading section .rodata, size 0xab630 lma 0x80354638
Loading section .data, size 0xf3828 lma 0x803ffc68
Loading section .ctors, size 0x68 lma 0x804f3490
Loading section .dtors, size 0x44 lma 0x804f34f8
Loading section .devtab, size 0x792c lma 0x804f353c
Start address 0x800400bc, load size 4959848
Transfer rate: 10 KB/sec, 666 bytes/write.
(gdb) step
warning: GDB can't find the start of the function at 0x8000c44c.

    GDB is unable to find the start of the function at 0x8000c44c
and thus can't determine the size of that function's stack frame.
This means that GDB may be unable to access that stack frame, or
the frames below it.
    This problem is most likely caused by an invalid program counter or
stack pointer.
    However, if you think GDB should simply search farther back
from 0x8000c44c for code which looks like the beginning of a
function, you can increase the range of the search using the `set
heuristic-fence-post' command.
Cannot find bounds of current function
(gdb) continue
Continuing.

Unfortunately my software application is not running as expected. It seems to me that the app won`t be executed at all. Using Redboot bootloader to download the elf image by xmodem (at 0x80040000) I just use the command go 0x800400BC and the programm will run.  

Do you have any hints where the problem could be?

best regards
Bernd





> 
> John Dallaway
> eCos maintainer
> http://www.dallaway.org.uk/john
> 
> -- 
> Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
> and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
> 

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Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
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Re: [ECOS] Re: GDB stub support

[Bernd Schuster]

here`s "where" output: 

(gdb) where
#0  0x8000c44c in ?? ()
#1  0x800400bc in debug_vector ()
    at /home/.../build/../eCos/packages/hal/mips/arch/current/src/vectors.S:131
#2  0x80000ab8 in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
(gdb) 


best regards
Bernd

-------- Original-Nachricht --------
> Datum: Tue, 18 Dec 2012 10:28:13 +0000
> Von: John Dallaway <john@dallaway.org.uk>
> An: schuster_bernd@gmx.net
> CC: eCos Discussion <ecos-discuss@ecos.sourceware.org>
> Betreff: [ECOS] Re: GDB stub support

> Bernd
> 
> On 17/12/12 21:04, Bernd Schuster wrote:
> 
> >> It is perfectly feasible to use a single channel for both debug and
> >> diagnostics as you suggest. You should configure eCos (for your
> >> application build) with CYG_HAL_STARTUP == "RAM" and with
> >> CYGSEM_HAL_USE_ROM_MONITOR enabled. You should then find that (by
> >> default) diagnostic/trace messages from your application are routed via
> >> the GDB stub and appear within your GDB session on the host.
> > 
> > That means, it is much more comfortable to download only the redboot
> > bootloader to my flash memory and download the application (eCos O/S
> > together with my own software app) by GDB instead of having already
> > everything installed on my MIPS board? I asked this because it will
> > take some time to download the application by serial port instead of
> > being able to download a new file by ethernet. 
> 
> If you have ethernet support built into RedBoot you should also be able
> to connect to the GDB stub via TCP for faster download. The default port
> number is 9000, so the GDB command would be:
> 
>   target remote <target IP address>:9000
> 
> > I already found the specific ecm file where 
> > cdl_component CYG_HAL_STARTUP {
> >     user_value ROMRAM
> > };
> > I have to specify RAM instead of ROMRAM. It seams that
> > CYGSEM_HAL_USE_ROM_MONITOR is already enabled if I use RAM instead of
> > ROMRAM. 
> 
> That makes sense.
> 
> >> For avoidance of doubt, you can use the GDB "load" command to download
> >> your application to RAM when debugging an application configured for
> RAM
> >> startup. It is not necessary to load it at the "RedBoot>" prompt.
> > 
> > Do I have to specify the correct RAM-addr where the application has to
> be
> > downloaded? Because the load command consists only of "load filename".
> 
> If you specify the ELF executable filename when you launch GDB then
> symbols will be loaded automatically. You can just use "load" with no
> filename and "continue" to start execution. The section records in the
> elf file will indicate where each section must be loaded. You do not
> need to specify the addresses manually.
> 
>   bash$ mipsisa32-elf-gdb myProgram.elf
>   (gdb) target remote <your parameters>
>   (gdb) load
>   (gdb) break web_init
>   (gdb) continue
> 
> I hope this helps...
> 
> John Dallaway
> eCos maintainer
> http://www.dallaway.org.uk/john
> 
> -- 
> Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
> and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
> 

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Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
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