[fpc-devel] Building cross-compiler for arm-linux on win32

[Nikolai Zhubr]

Hi,

16.12.2018 13:51, I wrote:
[...]
> So inserting
> ASTARGET+=-mfpu=softvfp
> allowed full cross-build to succeed. I have yet to see if the generated
> binaries are actually usable.

Ok, now the resulting elf executable has this (supposedly correct) flag:
private flags = 600: [APCS-32] [VFP float format] [software FP]

And, helloworld still fails to run:
Illegal instruction

And, I still see tons of "ARM BLX instruction ..." warnings from ld of 
this kind:

C:\FPC\3.0.4\bin\i386-Win32\arm-linux-ld.exe: 
arm\units\arm-linux\rautils.o: warning: ARM BLX instruction targets ARM 
function 'SYSTEM_$$_POS$CHAR$SHORTSTRING$$LONGINT'
C:\FPC\3.0.4\bin\i386-Win32\arm-linux-ld.exe: 
arm\units\arm-linux\rautils.o: warning: ARM BLX instruction targets ARM 
function 'fpc_shortstr_copy'
C:\FPC\3.0.4\bin\i386-Win32\arm-linux-ld.exe: 
arm\units\arm-linux\rautils.o: warning: ARM BLX instruction targets ARM 
function 'fpc_shortstr_to_shortstr'
C:\FPC\3.0.4\bin\i386-Win32\arm-linux-ld.exe: 
arm\units\arm-linux\rautils.o: warning: ARM BLX instruction targets ARM 
function 'SYSTEM_$$_DELETE$OPENSTRING$LONGINT$LONGINT'

Currently, my build command is:
make OS_TARGET=linux CPU_TARGET=arm NOGDB=1 CROSSCOMPILE=1 
CROSSOPT="-CpARMV6 -Cfsoft" all

Any hints?


Thank you!

Regards,
Nikolai

>
>
> Thank you!
>
> Regards,
> Nikolai
>
>>
>>
>> Thank you!
>>
>> Regards,
>> Nikolai
>>
>>> Thing is, object files compiled from pascal (like system.o) still get
>>> this suspicious VFP flag even after I started using CROSSOPT="-CpARMV6
>>> -Cfsoft". However, object files compiled from assembler sources (like
>>> prt0.o) does not. I'm trying to find where it comes from.
>>>
>>> arm-linux-objdump.exe -p prt0.o
>>> prt0.o: file format elf32-littlearm
>>> private flags = 0: [APCS-32] [FPA float format]
>>>
>>> arm-linux-objdump.exe -p system.o
>>> system.o: file format elf32-littlearm
>>> private flags = 600: [APCS-32] [VFP float format] [software FP]
>>>
>>> As a side note, I suddenly realised that I don't need any specially
>>> crafted version of binutils as long as I target linux and build binutils
>>> from source. Standard binutils source tar compiles with almost zero
>>> effort on modern mingw, at least for linux target.
>>>
>>>
>>> Thank you!
>>>
>>> Regards,
>>> Nikolai
>>>
>>>
>>> 15.12.2018 23:23, I wrote:
>>>> Still can not understand this ".o uses VFP instructions, whereas .\pp
>>>> does not", but because I build binutils myself I've found and disabled
>>>> the ld error exit on (in_flags & EF_ARM_VFP_FLOAT) != (out_flags &
>>>> EF_ARM_VFP_FLOAT), and then with such "fixed" binutils crossfpc build
>>>> completed somehow. I can now produce arm-linux executables, but
>>>> probably
>>>> something is wrong anyway because this "VFP float format" is present in
>>>> .o files but not in final elf executables:
>>>>
>>>> arm-linux-objdump.exe -p t.o
>>>> t.o: file format elf32-littlearm
>>>> private flags = 400: [APCS-32] [VFP float format]
>>>>
>>>> arm-linux-objdump.exe -p t
>>>> t: file format elf32-littlearm
>>>> Program Header:
>>>> ......
>>>> private flags = 0: [APCS-32] [FPA float format]
>>>>
>>>> (t.pas is a helloworld one-liner.)
>>>>
>>>> Besides, I get tons of warning from ld like this:
>>>> C:\FPC\3.0.4\bin\i386-Win32\arm-linux-ld.exe:
>>>> C:\FPC\3.0.4\units\arm-linux\rtl\system.o: Warning: Arm BLX instruction
>>>> targets Arm function 'SYSTEM_$$_SYSINITSTDIO'.
>>>>
>>>> It looks like literally every function in every unit produce such a
>>>> "Arm
>>>> BLX instruction" warning. Seems suspicious.
>>>>
>>>> And finally, on the target board, the executable totally fails with:
>>>>
>>>> "Illegal instruction"
>>>>
>>>> Any hints?
>>>>
>>>>
>>>> Thank you!
>>>>
>>>> Regards,
>>>> Nikolai
>>>>
>>>>> It successfully produced object files, but ld refsuses to link them.
>>>>> Again, the message is:
>>>>> pp.o uses VFP instructions, whereas .\pp does not
>>>>> (lots of these repeated)
>>>>>
>>>>> I'm guessing is that either some option is missing for ld to actually
>>>>> accept that VFP is present, or rather I need to rebuild my binutils
>>>>> for
>>>>> a different (hard fp) target?
>>>>>
>>>>> (The exact call that fails now is arm-linux-ld.exe -s -L. -o .\pp
>>>>> .\link.res)
>>>>>
>>>>>
>>>>> Thank you!
>>>>>
>>>>> Regards,
>>>>> Nikolai
>>>>>
>>>>>>
>>>>>>
>>>>>>
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