[LinuxBIOS] Calling non-PIC code from PIC code

[Carl-Daniel Hailfinger]

Hi Segher,

thanks for looking into this! As per your request on IRC, attached are
the files which comprise the XIP code we are having problems with.
*.85.* has the non-extern variant of initram_printktest.c and does abort
with a linker error (duplicate symbols), *.86.* has the extern variant
and links fine.

Short list of files with explanations:
build/stage0-prefixed.85.o
build/stage0-prefixed.86.o
Object we link against with --just-symbols. It contains the non-PIC code
we want to call.

build/mainboard/emulation/qemu-x86/initram_xip.85.o
build/mainboard/emulation/qemu-x86/initram_xip.86.o
PIC object with "ret (*func)(args) = stage0_##func;" sequence, contains
main(), which calls printk() and printktest().

build/mainboard/emulation/qemu-x86/initram_printktest_xip.85.o
PIC object with "ret (*func)(args) = stage0_##func;" sequence, contains
printktest(), which calls printk().

build/mainboard/emulation/qemu-x86/initram_printktest_xip.86.o
PIC object with "extern ret (*func)(args);" sequence, contains
printktest(), which calls printk().

initram_printktest.85.i
initram_printktest.85.s
initram_printktest.86.i
initram_printktest.86.s
Preprocessed output of the above.

initram.85.i
initram.85.s
initram.86.i
initram.86.s
Assembler output of the above.

shortlog.85.txt
shortlog.86.txt
gcc/ld commands used.

build/linuxbios.initram.86.o
Final linked object. build/linuxbios.initram.85.o did not link.

Call sequence is as follows:

initram.c:main()

->printk()->stage0_printk()

->printk()->stage0_printk()

->printktest1()

    ->printk()->stage0_printk()
->printk()->stage0_printk()

->initram_printktest.c:printktest()
    ->printk()->stage0_printk()  -----dies here


The generated code for printktest() is what we have problems with.

Regards,
Carl-Daniel
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