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From: Arnd Bergmann <arnd@arndb.de>
To: cbe-oss-dev@ozlabs.org
Subject: Re: [Cbe-oss-dev] [PATCH] force -mno-string option on cell
Date: Fri, 23 Mar 2007 21:46:20 +0100
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Cc: Akinobu Mita <mita@fixstars.com>,
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On Friday 23 March 2007, Segher Boessenkool wrote:

> =A0=A0=A0=A0=A0=A0=A0=A0CFLAGS_whatever.o :=3D -msome-flags
>=20
> It would be even better to not lie to the compiler by
> telling it it can use the LS area as normal memory, since
> evidently it cannot :-)

Yes, this is the important point. I actually think the first
patch that just replaces memcpy with memcpy_fromio is the
right solution for the specific problem.

Avoiding certain instructions in the kernel may be a good
thing to do as well, but this is not at all a cell specific
thing.

Maybe we should have a more detailed CPU selection Kconfig
option like

CPU Family
   * 64 bit common (power3/4/5/6, ppc970, cell, *star)
   * 32 bit common (6xx, 82xx, 83xx, 86xx)
   * 40x/44x
   * ...

Minimum supported CPU (gcc -march=3D, depending on above selection)
   * 603
   * 604
   * 750
   * power3
   * power4
   * 970

Optimize for CPU (gcc -mtune)
   (subset of the -march list as before)

	Arnd <><