From: Tom Rini <trini@kernel.crashing.org>
To: Juergen Beisert <jbeisert@eurodsn.de>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: dcbz-instruction on PPC405GP
Date: Fri, 11 Jul 2003 09:31:23 -0700 [thread overview]
Message-ID: <20030711163123.GY17433@ip68-0-152-218.tc.ph.cox.net> (raw)
In-Reply-To: <200307111623.45470.jbeisert@eurodsn.de>
On Fri, Jul 11, 2003 at 04:23:45PM +0200, Juergen Beisert wrote:
> I want to speed up some data copy in my Linux driver and so I want to use the
> dcbz-instruction.
> I get the memory with a kmalloc()-call with GFP_KERNEL argument. After that I
> call a small assembler routine that uses dcbz to set this memory to zero. I
> am shure this memory starts at 32 byte boundary and ends at another 32 byte
> boundary. But if I call the dcbz-instruction I get an alignment exception.
> I have tried to test the "Write Trough" and "Caching Inhibit" bits for this
> TLB, but I'm not shure that I have found the right one. I have called
> get_pteptr() with the kmalloc() returned virtual address. Is this the right
> way to get informations about this TLB? The returned value seems ok (caching
> enabled and write back, if Linux uses the same bit positions like the 405GP
> manual).
> With caching enabled and write back the dcbz-instruction should work (that's
> what I have read in the manual). Right?
Why are you not calling memset on this region instead?
--
Tom Rini
http://gate.crashing.org/~trini/
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2003-07-11 16:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-11 14:23 dcbz-instruction on PPC405GP Juergen Beisert
2003-07-11 16:31 ` Tom Rini [this message]
2003-07-14 7:09 ` Juergen Beisert
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