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

Joost van der Sluis joost at cnoc.nl
Tue Aug 16 17:26:47 CEST 2005

On Tue, 2005-08-16 at 16:14 +0200, Jonas Maebe wrote:
> 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.

Ok, it seems like that they don't compile on ppc at all. They use a
mainframe with a 'couple of POWER5 (gr), at 1655.992000MHz'

If I understood correctly they don't support Altivec (VMX?) and are
there some other issues.

Is it possible at all to make a power-port? Maybe the power also has the
cache-issue, and is that the main problem?

If someone is willing to look at it, but doesn't have a POWER5 machine,
he can try to get an account on the Linux on POWER-challende machines?

Any thoughts on this?

Met vriendelijke groeten,

  Joost van der Sluis
  CNOC Informatiesystemen en Netwerken

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