JTAG debugger recommendations? - Embedded

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  1. JTAG debugger recommendations?

    Does anyone have any recommendations for a good JTAG debugger for
    Linux applications and modules? We are running Linux 2.4 with a
    Freescale MPC8248 processor.

    Thank you.


  2. Re: JTAG debugger recommendations?

    On Fri, 24 Aug 2007 16:33:45 -0700, Bill wrote:

    >Does anyone have any recommendations for a good JTAG debugger for
    >Linux applications and modules? We are running Linux 2.4 with a
    >Freescale MPC8248 processor.

    Why not use GDB?

  3. Re: JTAG debugger recommendations?

    On Aug 27, 12:42 pm, Thomas Lykkeberg wrote:
    > On Fri, 24 Aug 2007 16:33:45 -0700, Bill wrote:
    > >Does anyone have any recommendations for a good JTAG debugger for
    > >Linux applications and modules? We are running Linux 2.4 with a
    > >Freescale MPC8248 processor.

    >
    > Why not use GDB?


    GDB affects the timing to the point that our system does not run.


  4. Re: JTAG debugger recommendations?

    On Aug 25, 9:33 am, Bill wrote:
    > Does anyone have any recommendations for a good JTAG debugger for
    > Linux applications and modules? We are running Linux 2.4 with a
    > Freescale MPC8248 processor.
    >
    > Thank you.


    Try the Abatron BDI2000. Thats what I am using, and gives source
    level debugging (with MMU support) using a GDB server. It is straight
    forward to setup and works well.


  5. Re: JTAG debugger recommendations?

    On Aug 27, 5:08 pm, Janaka wrote:
    > On Aug 25, 9:33 am, Bill wrote:
    >
    > > Does anyone have any recommendations for a good JTAG debugger for
    > > Linux applications and modules? We are running Linux 2.4 with a
    > > Freescale MPC8248 processor.

    >
    > > Thank you.

    >
    > Try the Abatron BDI2000. Thats what I am using, and gives source
    > level debugging (with MMU support) using a GDB server. It is straight
    > forward to setup and works well.


    We tried the Abatron BDI2000 and it adversely affected our system. We
    have a modem running 10 ms frames, which is very sensitive if the
    timing is changed.


  6. Re: JTAG debugger recommendations?

    > Why not use GDB?

    AFAIK, GDB _uses_ the JTAG debug hardware if configured accordingly. Am
    I wrong ?

    -Michael

  7. Re: JTAG debugger recommendations?

    > We tried the Abatron BDI2000 and it adversely affected our system. We
    > have a modem running 10 ms frames, which is very sensitive if the
    > timing is changed.


    How can that be ? The BDM/JTAG interface is supposed to do nothing as
    long long as you don't stop the execution. Is this not true ?

    -Michael

  8. Re: JTAG debugger recommendations?

    On 2007-08-28, Bill wrote:
    > On Aug 27, 5:08 pm, Janaka wrote:
    >> On Aug 25, 9:33 am, Bill wrote:
    >>
    >> > Does anyone have any recommendations for a good JTAG debugger for
    >> > Linux applications and modules? We are running Linux 2.4 with a
    >> > Freescale MPC8248 processor.

    >>
    >> > Thank you.

    >>
    >> Try the Abatron BDI2000. Thats what I am using, and gives source
    >> level debugging (with MMU support) using a GDB server. It is straight
    >> forward to setup and works well.

    >
    > We tried the Abatron BDI2000 and it adversely affected our system. We
    > have a modem running 10 ms frames, which is very sensitive if the
    > timing is changed.


    Isn't any JTAG debugger is going to affect timing since it has
    to stop the processor to do any "debugging"? I remember some
    ARM vendors bragging about how they had non-intrusive tracing
    via JTAG, but I'm very skeptical.

    --
    Grant Edwards grante Yow! Are you the
    at self-frying president?
    visi.com

  9. Re: JTAG debugger recommendations?

    On Aug 28, 12:26 am, Michael Schnell
    wrote:
    > > We tried the Abatron BDI2000 and it adversely affected our system. We
    > > have a modem running 10 ms frames, which is very sensitive if the
    > > timing is changed.

    >
    > How can that be ? The BDM/JTAG interface is supposed to do nothing as
    > long long as you don't stop the execution. Is this not true ?
    >
    > -Michael


    All I can do is speak from experience.


  10. Re: JTAG debugger recommendations?


    "Bill" wrote in message
    news:1188320885.277334.36590@r23g2000prd.googlegro ups.com...
    > On Aug 28, 12:26 am, Michael Schnell
    > wrote:
    > > > We tried the Abatron BDI2000 and it adversely affected our system. We
    > > > have a modem running 10 ms frames, which is very sensitive if the
    > > > timing is changed.

    > >
    > > How can that be ? The BDM/JTAG interface is supposed to do nothing as
    > > long long as you don't stop the execution. Is this not true ?
    > >
    > > -Michael

    >
    > All I can do is speak from experience.
    >


    10 ms is an eternity on most modern processors. A real JTAG emulator should
    have zero affect on the execution of your code. In fact a debugger shouldn't
    affect timing while your code is running. I think you have something else
    going on.

    Are you using a different build script/makefile when you are
    debugging/emulating? A lot of times the compiler needs different options to
    retain the symbol information that the emulator uses. Maybe you're
    inadvertently changing the optimization level of your compiler and ending up
    with slower code as a result. If it is a c compiler, for example, there is
    usually a -Ox command line option to set the optimization level.

    -Clark



  11. Re: JTAG debugger recommendations?

    On Aug 30, 11:21 am, "cpope" wrote:
    > "Bill" wrote in message
    >
    > news:1188320885.277334.36590@r23g2000prd.googlegro ups.com...
    >
    > > On Aug 28, 12:26 am, Michael Schnell
    > > wrote:
    > > > > We tried the Abatron BDI2000 and it adversely affected our system. We
    > > > > have a modem running 10 ms frames, which is very sensitive if the
    > > > > timing is changed.

    >
    > > > How can that be ? The BDM/JTAG interface is supposed to do nothing as
    > > > long long as you don't stop the execution. Is this not true ?

    >
    > > > -Michael

    >
    > > All I can do is speak from experience.

    >
    > 10 ms is an eternity on most modern processors. A real JTAG emulator should
    > have zero affect on the execution of your code. In fact a debugger shouldn't
    > affect timing while your code is running. I think you have something else
    > going on.
    >
    > Are you using a different build script/makefile when you are
    > debugging/emulating? A lot of times the compiler needs different options to
    > retain the symbol information that the emulator uses. Maybe you're
    > inadvertently changing the optimization level of your compiler and ending up
    > with slower code as a result. If it is a c compiler, for example, there is
    > usually a -Ox command line option to set the optimization level.
    >
    > -Clark


    I don't know what the 10ms Bill referred to, but a JTAG device could
    take this much time depending on the interfaces used to communicate
    with the JTAG itself. For example if your JTAG device is USB / Serial
    or Network, the time taken for the debugger to communicate with the
    JTAG may be more than 10ms. Hence you get the impression that the
    actual code execution takes that time. From my understanding it
    depends on the following factors.
    - JTAG debugger -server side (eg: GDB server)
    - Debugger - client side (GDB)
    - Connection to JTAG (eg: serial port)
    - How the debugger communicates (given that usually JTAGs have limited
    number of HW breakpoints [eg: 2]). Does it set a breakpoint on each
    source line or is it smart enough to set breakpoints in optimised
    code .... etc.etc.

    JTAG itself should not have any effect on the timing (baring track
    lengths, which is in pS or uS timing and internal CPU HW delays), but
    how you communicate with the JTAG pod will have a lot of bearing.
    Cheers
    J


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