Re: NEED_REGISTER_FRAME_INFO can be replaced by -static-libgcc

[Vladimir 'φ-coder/phcoder' Serbinenko]

Christian Franke wrote:
> Vladimir 'φ-coder/phcoder' Serbinenko wrote:
>> Christian Franke wrote:
>>   
>>> The *_frame_info symbols are set undefined to force linkage of the
>>> libgcc_s shared library or dll.
>>>
>>> This can be prevented by TARGET_LDFLAGS=-static-libgcc. To build from
>>> grub-1.98 tarball on Cygwin, run configure with this argument.
>>>
>>> May also be necessary on other build platforms when -shared-libgcc is
>>> the default. It may be possible simply set -static-libgcc
>>> unconditionally.
>>>
>>>      
>> We already supply -lgcc --static-libgcc. Do you know why it still had
>> issues?
>>    
>
> The above is only set when linking the kernel image.
>
> According to 'gcc -dumpspecs' of Cygwin gcc 4.3.4-3, options '-u
> ___[de]register_frame_info' are always passed to the linker if
> -static-libgcc is not specified. This is Cygwin and MinGW specific: In
> the exe startup code these symbols are loaded only if present, so the
> DLL must be forced to load first.
>
> As a consequence, the symbols are also set undefined when the GRUB
> pre-*.o files are generated with 'ld -r'.
>
> The attached patch works for me with the bzr revision preceding the
> NEED_REGISTER_FRAME_INFO fix.
>
Doesn't it risk linking e.g. __bswapsi2 into every module which uses it
during partial link? It would increase module size on RISC
>
>> And I also doubt usefullness of pulling these functions since reference
>> to them is purely dummy: no relocation uses it so it will only increase
>> code size. Another concern is the behviour of these functions in grub
>> environment if they ever get called.
>>
>>    
>
> AFAICS from the gcc source, the functions are used in EH stack
> unwinding code in libgcc. The compiler itself does not generate calls
> to these functions.
>
>
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-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

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