Re: [Ltib] Forcing DEBUG for pr_debug in kernel driver through LTIB

[Stuart Hughes]

Hi Franz,

During kernel configuration if you press the '/' key and enter the 
symbol you're looking for (without the leading  CONFIG_) it should show 
you the dependencies you need to enable to make it visible and select it.

Note: I don't think CONFIG_DEBUG_KERNEL turns on kernel debug messages, 
I think it's more about setting -g during the build to add symbols. 
I'm not sure and you may be better asking some kernel experts.

Regards, Stuart


Franz Trierweiler wrote:
> Stuart Hughes a écrit :
> > Hi Franz,
> >
> > As far as ltib goes, you can do: ./ltib -p kernel -c and that will 
> > unpack the kernel sources and drop you to the kernel config screen.  
> > If the kernel config system has a configuration pooint to set 
> > KERN_DEBUG then you can set it there, save and exit and the kernel 
> > will build.  If there is no config point for it, you'll have to edit 
> > the file manually.
> >
> > Regards, Stuart
> >
> > Franz Trierweiler wrote:
> > > Hello everybody
> > >
> > > Freescale has just issued a new PDK (PDK 1.6) for the iMX25 3-stack 
> > > evalboard. I have hardwired a SIM interface to my evalboard so that I 
> > > can scope all electrical signals coming from that cell. The fact is 
> > > that I am trying to debug the mxc_sim.c source file for this SIM 
> > > interface. mxc_sim is a SIM driver. In order to achieve this, I would 
> > > like to enable pr_debug (...) output to my console when this driver 
> > > is running and watch all debug messages displayed.
> > >
> > > The kernel.h shows the pr_debug macro like this:
> > >
> > > /* If you are writing a driver, please use dev_dbg instead */
> > > #if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
> > > #define pr_debug(fmt, ...) do { \
> > >    dynamic_pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
> > >    } while (0)
> > > #elif defined(DEBUG)
> > > #define pr_debug(fmt, ...) \
> > >    printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> > > #else
> > > #define pr_debug(fmt, ...) \
> > >    ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
> > > #endif
> > >
> > > There seems that if I #define DEBUG somewhere then I will have the 
> > > messages displayed (or logged) somewhere.
> > >
> > > Is there a way of doing this properly in the LTIB configuration when 
> > > recompiling the kernel ?
> > >
> > > Or should I simply #define DEBUG in kernel.h? (This really does not 
> > > sound the right way).
> > >
> > > Or should I simply put DEBUG=ON (or something like this) in the LTIB 
> > > perl script? (sounds also very dirty).
> > >
> > > I really would like to make this in a clean way.
> > >
> > > Regards,
> > > Franz
> Hi Stuart,
>
> There is no configuration point for KERN_DEBUG but I found a few 
> references to DEBUG in 
> ~/ltib/config/platform/imx/imx25_3stack_defconfig.dev
>
> #
> # Kernel hacking
> #
> # CONFIG_PRINTK_TIME is not set
> CONFIG_ENABLE_WARN_DEPRECATED=y
> CONFIG_ENABLE_MUST_CHECK=y
> CONFIG_FRAME_WARN=1024
> # CONFIG_MAGIC_SYSRQ is not set
> # CONFIG_UNUSED_SYMBOLS is not set
> # CONFIG_DEBUG_FS is not set
> # CONFIG_HEADERS_CHECK is not set
> # CONFIG_DEBUG_KERNEL is not set
> # CONFIG_DEBUG_BUGVERBOSE is not set
> # CONFIG_DEBUG_MEMORY_INIT is not set
> CONFIG_FRAME_POINTER=y
> # CONFIG_RCU_CPU_STALL_DETECTOR is not set
> # CONFIG_LATENCYTOP is not set
> CONFIG_SYSCTL_SYSCALL_CHECK=y
> CONFIG_HAVE_FUNCTION_TRACER=y
>
> It is recommended not to edit this file. Thus, I suspect there is a 
> clean way of configuring CONFIG_DEBUG_KERNEL through LTIB. I invoked 
> ltib with --configure and chose "Configure the kernel" (as usual) but 
> never was successfull in finding the corresponding options. The 
> --configure option makes changes in 
> ~/ltib/config/platform/imx/imx25_3stack_defconfig.dev, thus I suspect I 
> am not too far from what I am looking for.
>
> I will try to modify the file by hand.
>
> Regards,
> Franz