Re: [beagleboard] Tools to debug the driver .

[John Syne]

Well, you won’t be able to do much. For example, as you single step, the kernel 
can switch tasks and then you will be stepping through an unrelated thread. No 
way to switch back to your original thread, so you will have to set breakpoints 
in the source and hope to get back to your original code. Second, you cannot 
debug Kernel Modules because you don’t know the address of the module. There 
are several other limitations, but you get my point when the debugger isn’t 
kernel aware. 

TI use to have some limited kernel awareness in CCS4, but removed that 
functionality in CCSV5 because they wanted to stay as close to the Eclipse 
releases so heavy customization was out. I know the TI CCS developers and they 
explained that I was one of the only developers asking for kernel awareness. 
Perhaps if more developers asked for this feature, they might add it back in. 

Regards,
John




> On Jun 14, 2016, at 11:17 AM, arnout.diels...@gmail.com wrote:
> 
> Hi,
> 
> An experience:
> I can debug the linux kernel with both openocd + TIAO/flyswatter2/.. or the 
> TI dongles like blackhawk with CCS.
> 
> Note, one very tricky thing: Recent linux kernels mess with the jtag during 
> boot on the bbb. You need a kernel patch -just- to be able to debug:
> 
>  diff arch/arm/mach-omap2/omap_hwmod_33xx_data.c
> diff --git a/arch/arm/mach-omap2/omap_hwmod_33xx_data.c 
> b/arch/arm/mach-omap2/omap_hwmod_33xx_data.c
> index 6b406ca..8cb0b85 100644
> --- a/arch/arm/mach-omap2/omap_hwmod_33xx_data.c
> +++ b/arch/arm/mach-omap2/omap_hwmod_33xx_data.c
> @@ -223,6 +223,7 @@ static struct omap_hwmod am33xx_debugss_hwmod = {
> .class  = _debugss_hwmod_class,
> .clkdm_name = "l3_aon_clkdm",
> .main_clk   = "trace_clk_div_ck",
> +   .flags  = (HWMOD_INIT_NO_IDLE | HWMOD_INIT_NO_RESET),/*Added this 
> line*/
> .prcm   = {
> .omap4  = {
> .clkctrl_offs   = 
> AM33XX_CM_WKUP_DEBUGSS_CLKCTRL_OFFSET,
> 
> 
> Op donderdag 5 mei 2016 06:52:22 UTC+2 schreef Raul Piper:
> Is TIN FlysWatter2  a 
> better tool for debugging the kernel driver in BBB.Can some one please post 
> thier experience?
> -Rp
> 
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Re: [beagleboard] Tools to debug the driver .

[John Syne]

I completely agree with Vesa comments and I believe Lauterbach is the gold 
standard when it comes to Kernel Aware debugging. It is a difficult tool to 
learn but it is very powerful and has everything you need to get the job done. 
I have learned a lot just using the T32.

Several years ago, I worked with the CCSV4 developers at TI and they did manage 
to get a decent kernel aware debugger working, but they dropped those features 
in CCSV5 because they wanted to stay closer to the Eclipse base environment so 
that upgrades to newer Eclipse releases was easier. Their plan was to add Linux 
Kernel aware debugging, but later decided that there wasn’t enough interest to 
justify the investment. As of CCSV6, they still don’t have Linux kernel ware 
debugging. From what they told me, I was one of the few users who was asking 
for Linux Kernel aware debugging. At that time, I made the switch to Lauterbach 
and have never looked back. 

I also use BDI2000/BDI3000 from Abatron and PEEDi from Ronetix which act as a 
gdbserver so any GDB compatible debug app can be used for debugging. While they 
do have some kernel aware debugging capabilities, they are no ware as 
comprehensive as Lauterbach. 

Regarding FlySwatter2, you are better off purchasing a Blackhawk USB200 which 
cost less than $100 and it works fine with CCSV6. FlySwatter requires a lot of 
work on your behalf to make it work.

Regards,
John




> On May 5, 2016, at 1:06 AM, Vesa Jääskeläinen  wrote:
> 
> Hi,
> 
> If you really want to work with Linux JTAG debugging you need to have a JTAG 
> debugger and debugging software that is really Linux aware. There aren't many 
> available that really support both kernel and app debugging at the same time 
> for Linux using JTAG connectivity.
> 
> You may want to check out Peter Griffin's GDB and Linux Kernel Awareness 
> slides from Embedded Linux Conference Europe 2015:
> http://events.linuxfoundation.org/sites/events/files/slides/ELC-E%20Linux%20Awareness.pdf
> 
> If you want to save your time and do your work today I recommend paying a bit 
> more than that and go for even for entry level Lauterbach's Power Debug 
> debugger. Their software (Trace32) is not pretty for today's standards but 
> has bunch of features that makes your life easier. There is slight learning 
> curve for the tool but once that is done it gets your work done. Price is 
> thou 4 number figure (in euros/dollars -- lower half).
> 
> If you are looking for ARM DS-5 -- it has also some features and a bit 
> shinier user interface (in some places) but currently lacks in some features 
> that are found in Trace32 -- perhaps biggest is co-debugging over JTAG for 
> Kernel and Applications at the same time, next missing feature is general 
> flexibility I suppose. This same story matches quite a lot of debugging 
> software currently available. DS-5's system profiler is something that might 
> be interest for some.
> 
> If you want to play around with open source alternatives -- especially then 
> check the presentation above.
> 
> Also note that BBB has TI's Compact JTAG connector -- so get matching adapter 
> and solder the socket.
> 
> TI has done some work with their Code Composer Studio and then there are some 
> low cost JTAG debuggers that are compatible with the tool -- you are locked 
> to TI's ecosystem but that might also be something to consider. It also 
> exposes some "homemade" features of TI processors. Haven't used the tool for 
> Linux kernel debugging but there might be someone here with experience with 
> the tool for that purpose.
> 
> And if someone has other kind of experiences in here I would love to hear :) 
> both OSS and commercial solutions are in interest.
> 
> Thanks,
> Vesa Jääskeläinen
> 
> On 05/05/16 07:52, Raul Piper wrote:
>> Is TIN FlysWatter2  a 
>> better tool for debugging the kernel driver in BBB.Can some one please post 
>> thier experience?
>> -Rp
>> -- 
>> For more options, visit http://beagleboard.org/discuss
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>> You received this message because you are subscribed to the Google Groups 
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>>  
>> .
>> For more options, visit https://groups.google.com/d/optout.
> 
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Re: [beagleboard] Tools to debug the driver .

[Vesa Jääskeläinen]

Hi,

If you really want to work with Linux JTAG debugging you need to have a 
JTAG debugger and debugging software that is really Linux aware. There 
aren't many available that really support both kernel and app debugging 
at the same time for Linux using JTAG connectivity.


You may want to check out Peter Griffin's GDB and Linux Kernel Awareness 
slides from Embedded Linux Conference Europe 2015:

http://events.linuxfoundation.org/sites/events/files/slides/ELC-E%20Linux%20Awareness.pdf

If you want to save your time and do your work today I recommend paying 
a bit more than that and go for even for entry level Lauterbach's Power 
Debug debugger. Their software (Trace32) is not pretty for today's 
standards but has bunch of features that makes your life easier. There 
is slight learning curve for the tool but once that is done it gets your 
work done. Price is thou 4 number figure (in euros/dollars -- lower half).


If you are looking for ARM DS-5 -- it has also some features and a bit 
shinier user interface (in some places) but currently lacks in some 
features that are found in Trace32 -- perhaps biggest is co-debugging 
over JTAG for Kernel and Applications at the same time, next missing 
feature is general flexibility I suppose. This same story matches quite 
a lot of debugging software currently available. DS-5's system profiler 
is something that might be interest for some.


If you want to play around with open source alternatives -- especially 
then check the presentation above.


Also note that BBB has TI's Compact JTAG connector -- so get matching 
adapter and solder the socket.


TI has done some work with their Code Composer Studio and then there are 
some low cost JTAG debuggers that are compatible with the tool -- you 
are locked to TI's ecosystem but that might also be something to 
consider. It also exposes some "homemade" features of TI processors. 
Haven't used the tool for Linux kernel debugging but there might be 
someone here with experience with the tool for that purpose.


And if someone has other kind of experiences in here I would love to 
hear :) both OSS and commercial solutions are in interest.


Thanks,
Vesa Jääskeläinen

On 05/05/16 07:52, Raul Piper wrote:
Is TIN FlysWatter2  
a better tool for debugging the kernel driver in BBB.Can some one 
please post thier experience?

-Rp
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[beagleboard] Tools to debug the driver .

[Raul Piper]

Is TIN FlysWatter2  a 
better tool for debugging the kernel driver in BBB.Can some one please post 
thier experience?
-Rp

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