2011-09-21 14:33:55     Trouble with modules

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2011-09-21 14:33:55     Trouble with modules

Milind Paranjpe (UNITED STATES)

Message: 103480   

 

I'm working on bringing up uClinux on a custom BF527 board.  Things appear to be going quite well, except for the fact that I can't get any drivers compiled as modules to load properly on my kernel.  When I compile the kernel without modversions, any modules I load cause the kernel to crash.  On a kernel running with modversions, I get "unknown symbol" errors for simple symbols such as "printk" which show up in /proc/kallsyms.

 

For example, when I try to compile / load the sample_module example, I get the following output with modversions:

 

root:/mnt/app> insmod ./sample_module.ko

[  781.840000] sample_module: no symbol version for _driver_unregister

[  781.844000] sample_module: Unknown symbol _driver_unregister

[  781.848000] sample_module: no symbol version for _printk

[  781.852000] sample_module: Unknown symbol _printk

[  781.856000] sample_module: no symbol version for _driver_register

[  781.860000] sample_module: Unknown symbol _driver_register

[  781.864000] sample_module: no symbol version for _platform_bus_type

[  781.868000] sample_module: Unknown symbol _platform_bus_type

[  781.872000] sample_module: no symbol version for __mcount

[  781.876000] sample_module: Unknown symbol __mcount

insmod: can't insert './sample_module.ko': unknown symbol in module, or unknown parameter

root:/mnt/app> cat /proc/kallsyms | grep _driver_unregister

00101c10 T _sysdev_driver_unregister

00103518 T _driver_unregister

001044a4 T _platform_driver_unregister

00111c78 T _phy_driver_unregister

root:/mnt/app> cat /proc/version

Linux version 2.6.34.7-ADI-2010R1-gaab8a44-svn5 (xxxx@yyyy) (gcc version 4.3.5 (ADI-2010R1-RC4) ) #2 Tue Sep 20 17:19:29 PDT 2011

 

I'm using the 2010R1 branches of both uclinux-dist and linux-kernel for my baseline.  I have attached config files for both uClinux and the kernel.

 

Any clues would be much appreciated.

 

 

 

Milind

 

config.vendor-2.6.x

config.linux-2.6.x

config.device

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2011-09-21 23:26:38     Re: Trouble with modules

Aaron Wu (CHINA)

Message: 103489   

 

Have you tried to build it into the kernel? You may try this first to figure out where the problem happens, the module or the code of your driver.

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2011-09-21 23:40:55     Re: Trouble with modules

Milind Paranjpe (UNITED STATES)

Message: 103491   

 

Hi Aaron,

 

I haven't tried building the simple_module example into the driver, but with my setup I have observed that any driver included in the kernel that runs successfully when compiled into the kernel causes undefined-symbols or a crash when compiled as a module and loaded with modprobe or insmod.  One such example is g_ether.  If I compile this driver into the kernel it runs fine, but if I build it as a module and try "modprobe g_ether" I get undefined-symbols or crash depending on whether modversions is on or off.

 

Other things I have tried without being able to resolve this issue since posting the message earlier today:

 

    U-boot version 2010R1 instead of trunk

    Recompile toolchain from the head of 2010R1 branch instead of using precompiled 2010R1-RC4 binaries

    Slow down SCLK to 100 MHz and increase the value of EBIU_SDRRC to slow down SDRAM access

 

My goal is to eventually run my custom driver, hopefully as a module.  If I can't resolve this issue, I can try compiling it into the kernel as that appears to work on my setup.

 

Thanks,

 

Milind

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2011-09-22 12:14:03     Re: Trouble with modules

Milind Paranjpe (UNITED STATES)

Message: 103498   

 

All,

 

I was able to resolve this problem by modifying my linux-kernel config to match that provided for the EZKIT-V2 board as much as possible.  The revised config is attached.  I'm not really sure which of the options is the culprit, but if/when I have more time, I'll go back to identifying it.

 

I actually also modified arch/blackfin/Kconfig to make sure CONFIG_MEM_MT48LC32M16A2TG_75 was set as that's the SDRAM on my board; but I don't think this made any difference because CONFIG_BFIN_KERNEL_CLOCK is not set, and this means I end up using the SDRAM and clock parameters that are programmed by U-boot.

 

 

 

Milind

 

config.linux-2.6.x.revised

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