Re: gcc Cortex M4 bug ?

[Ilija Kocho <ilijak@siva.com.mk>]

On 13.06.2013 18:48, Kai Ruottu wrote:
> 13.6.2013 12:25, matti h kirjoitti:
>> Hi,
>> Im trying to implement a dynamic linker for M4 mcu's.
>> But the generated code from gcc seems incorrect to me: im compiling
>> using
>> arm-none-eabi-gcc: -mcpu=cortex-m4 -mthumb -O2 -ggdb 
>> -Wstrict-prototypes
>> -Wunused-parameter -lmylib main.c -o test
>
> For me this all looks insane :(
>
> I would expect the 'arm-eabi' target being purely static and not
> knowing anything about
> shared libraries and dynamic linking, something equivalent to the
> 'arm-elf' target but with
> somehow different object format. Meanwhile targets like 'arm-linux*',
> 'arm-*bsd' etc. will
> support dynamic linking. If we look at the Wikipedia page :
>
> http://en.wikipedia.org/wiki/Application_binary_interface
>
> there is told :
>
> "The main differences of an EABI with respect to an ABI for general
> purpose operating
> systems are that privileged instructions are allowed in application
> code, dynamic linking
> is not required (sometimes it is completely disallowed), and a more
> compact stack frame
> organization is used to save memory."

/Not required/ doesn't mean /not desirable/ (though /disallowed/
implies). It also doesn't mean that EABI hinders dynamic object loading.
An example is eCos (http://ecos.sourceware.org) that uses ARM EABI and
yet supports dynamic object loading.

Ilija