Re: [MiNT] Kernel compiling error

[Roberto Ferniani <rferniani@tiscali.it>]

On 10/06/2011 14:31, Vincent Rivière wrote:
> Roberto Ferniani wrote:
>> I've checked the cvs releases with the -D switch from  may 30 to  june
>> 04 and the make error appear only after that release. So something is
>> changed in the sources. I'm just curious to know why the 020-60 switch
>> was working before and not now.
> 
> I think this is a side effect of my ColdFire patch on 2011/06/03:
> http://www.atariforge.net/cgi-bin/cvsweb/freemint/sys/arch/Makefile.objs.diff?r1=text&tr1=1.12&r2=text&tr2=1.13&f=h
> 
> 
> Previously, mmu030.S was always compiled with -m68030, regardless to
> what general CPU option was used. After my patch, the general CPU option
> is also used to compile mmu030.S. No more exception.
> 
> Note that passing some CPU option to the *assembler* does not affect the
> optimization level, it simply allows or forbids the of use some
> instructions. For example, this is very handy for ColdFire: when an
> assembler source file compiles, there is no more unsupported instruction.
> 
> If I remember correclty, the GCC -m68020-60 option is actually -m68020
> *without* the instructions unsupported on 68060. I guess that the pmove
> instruction causing trouble here is supported on 68020 but not on 68060.
> Theoretically, -m68020-60 is worse than -m68020 because it uses only a
> subset of the 68020 instruction set, to be 68060 friendly. So really, in
> order to build any software optimally for a specific CPU, use the
> specific CPU option such as -m68030, and avoid a range option such as
> -m68020-60. Anyway, in that case, I suppose there are very few differences.
> Also, if I'm not wrong, with GCC 4.x -m68030 implies the usage of the
> FPU, so really mint030.prg is the best for you. Same for XaAES.
> 
Great infos, i'm going to google a little regarding the -m68030, fpu and
gcc 4, thank you!
Roberto