Re: [Geekos-devel] undefined reference to __bss_start

[David H. <da...@cs...>]

Ahmad Rizvi wrote:

> Hi,
>
> I am trying to make project 0, where I get an 'undefined reference to 
> __bss_start':
>
> geekos/mem.o(.text+0x3bf): In function `Init_BSS':
> ./src/geekos/mem.c:173: undefined reference to `__bss_start'
> geekos/mem.o(.text+0x3c7):../src/geekos/mem.c:173: undefined reference 
> to `__bss_start'
> make.exe: *** [geekos/kernel.exe] Error 1
>
> My environment is: windows (im trying to make geekos work on win, and 
> i removed all errors except this one), and the djgpp compiler (it is 
> gcc for dos). The error is caused by the reference in mem.c:

Note that djgpp has never been used for GeekOS development (that I know of).
You may encounter issues booting the kernel.  Also, it emits exes
in a.out format, so the ELF loading project won't work quite as
described.

>
> void Init_BSS(void)
> {
>    extern char BSS_END, BSS_START;
>    /* Fill .bss with zeroes */
>    memset(&BSS_START, '\0', &BSS_END - &BSS_START);
> }
>
> I did a little search, and the variable BSS_START is not defined in 
> any src file.
> I would like to know if the variable should be provided by the 
> compiler. It seems to be a mystery!
> Please shed some light on the situation.


Those symbols are defined in include/geekos/defs.h.  You'll need to
redefine them to whatever symbols are appropriate for djgpp.
It may be the case that you can just use the ones defined for
cygwin.

-Dave