question about libc.a libgcc.a

question about libc.a libgcc.a

[Hai Xu]

Dear all,

I am focus on a device driver. I compile it to a model.o and try to insmod
it to kernel. But when do so, I will get:

unresolved symbol: __udividi3
unresolved symbol: __umoddi3

As someone tell me, I have to link the libgcc.a to my model.o. I did it but
I when I try to insmod the model.o, I will get segamentation fault.

The following are my link libraries.
#LIBS    =
$(MATLAB_ROOT)/rtw/c/lib/$(ARCH)/lrtwLib.a -L/usr/lib/gcc-lib/i386-redhat-li
nux/2.96 -lgcc -L/usr/lib -lm -lc $(EXT_LIB) $(S_FUNCTIONS_LIB)
$(INSTRUMENT_LIBS)

Please give me some ideas about it.

Thanks in advance
Hai Xu

Re: question about libc.a libgcc.a

[Richard B. Johnson]

On Fri, 27 Jul 2001, Hai Xu wrote:

> Dear all,
> 
> I am focus on a device driver. I compile it to a model.o and try to insmod
> it to kernel. But when do so, I will get:
> 
> unresolved symbol: __udividi3
> unresolved symbol: __umoddi3
> 
> As someone tell me, I have to link the libgcc.a to my model.o. I did it but
> I when I try to insmod the model.o, I will get segamentation fault.
> 

[SNIPPED...]

You have some 64-bit divisions in your code. Make them shifts.
Everything in drivers will be powers-of-two (except some dumb
printk()s, where somebody tried to make decimals), so shifts
should work fine. If you have some offending decimal math, fix
it to display kbytes, megabytes, or gigabytes before you do
do integer decimal conversion. That way you never have to do
64-bit math.

Don't link in the 'C' runtime library.


Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.

Re: question about libc.a libgcc.a

[Russell King]

On Fri, Jul 27, 2001 at 02:55:59PM -0400, Hai Xu wrote:
> The following are my link libraries.
> #LIBS    =
> $(MATLAB_ROOT)/rtw/c/lib/$(ARCH)/lrtwLib.a -L/usr/lib/gcc-lib/i386-redhat-li
> nux/2.96 -lgcc -L/usr/lib -lm -lc $(EXT_LIB) $(S_FUNCTIONS_LIB)
> $(INSTRUMENT_LIBS)

Umm, if you're linking a kernel module, you can't:

1. link libm
2. link libc
3. use floating point in kernel

--
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html