Subject: Re: devel/cpuflags delivers wrong value on macppc (Power Mac G4)
To: David Brownlee <abs@NetBSD.org>
From: =?ISO-8859-1?Q?Timo_Sch=F6ler?= <firstname.lastname@example.org>
Date: 11/03/2004 19:10:37
> Just save the file from the email and run sh cpuflags.NetBSD
> should be fine :)
runs fine and gives -mcpu=7400
sorry for the noise =8-)
regarding to your link  to gnu's gcc doc and my link  to IBM, to
answer your question (which read)
> Those entried were probably added before gcc 3.1.x and the support
> for the -mcpu=7400 and -mcpu=7450
> Could you try the attached?
> It falls back to -mcpu=740 for versions of gcc before -mcpu=7400 and
> -mcpu=7450. Do you know of a better option?
i'd say to 'fall back' to the -mcpu=750 rather than 740.
AFAICT, the 740 is a 750 w/o L2 cache, so any G4 is more a 750-like CPU
than a 740-like, 'cos there are effectively no G4s w/o L2 cache
(remember that while the G3 uses the old 60x-style bus, the G4 features
the so-called MPX bus and _also_ supports the old 601 for backward
compatibility however ).
so optimization for a 750 (aka full-featured G3) would be best IMHO
(tho i really don't know whether gcc handles the lack of L2 cache for
the 740 that 'intensive')...
thanks so far!
 -- http://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_3.html#SEC32
 -- http://www.xlr8yourmac.com/G3CARDS/XLR8G4/G4vsG3.html