Building the Bootloader

[John David Anglin]

> It is not obvious to me that the C code is position independent.
> 
> >   The specific combination of flags allowed me to get something resembling
> >   a straight binary image (by ignoring the header) and position independence.
> >   For some reason I can't remember now, -fpic didn't get the job done
> >   (perhaps a compiler defect).
> 
> When -fpic is used, $global$ is not used as an offset to access data
> variables.  Gnu ld doesn't seem to like $global$ not being used:
> 
> 624 (hiauly1)dave> make
> hppa-linux-as                  ipl_s.s -o ipl_s.o
> ipl_s.s: Assembler messages:
> ipl_s.s:65: Warning: Ignoring subspace decl due to ELF BFD bugs.
> ipl_s.s:68: Warning: Ignoring subspace decl due to ELF BFD bugs.
> ipl_s.s:83: Warning: Ignoring subspace decl due to ELF BFD bugs.
> ipl_s.s:243: Warning: Ignoring subspace decl due to ELF BFD bugs.
> hppa-linux-gcc           -fwritable-strings -mdisable-fpregs -fpic -c ipl_c.c
> hppa-linux-gcc           -fwritable-strings -mdisable-fpregs -fpic -c rom_interf
> ace.c
> hppa-linux-ld                  -Ttext 0 -N ipl_s.o ipl_c.o rom_interface.o -L/eh
> ic/a/lib/gcc-lib/hppa-linux/egcs-2.91.60 -lgcc -o ipl
> ipl_c.o: In function `IPL_main':
> ipl_c.o($CODE$+0x60): undefined reference to `$global$'
> make: *** [ipl] Error 1

Here are Jeff Law's comments on using elf32-hppa with PIC: