[fpc-devel] Building for powerpc on FC4 seems to fail

Jonas Maebe jonas.maebe at elis.ugent.be
Tue Aug 16 16:14:18 CEST 2005

On 16 aug 2005, at 15:43, Joost van der Sluis wrote:

> i'm trying to build fpc 2.0.0 on the Fedora buildsystem, but the build
> fails for powerpc. The startcompiler gives a segfault.

The reason is probably that the machine you are building on is a G5.  
For some reason, the Linux kernel people do not turn on a  
compatibility bit in the G5 which guarantees the same behaviour for  
the dcbz instruction as on other PPC's (it's meaning is "fill a cache  
line with zeroes", but cache lines on G5's are 128 bytes as opposed  
to 32 bytes on other ppc's and many programs, including the FPC rtl,  
count on that -- which is the reason why this compatibility bit  
exists and why the G5 also has a dcbzl instruction which zeroes out a  
full 128 bytes in all cases).

Anyway, the result is that too much memory is zeroed out by some RTL  
routines. You can solve it by disabling all routines rtl/powerpc/ 
*.inc which include the dcbz instruction and then rebuilding the  
compiler on a non-G5 machine.


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