dcbz-instruction on PPC405GP

[Tom Rini]

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/

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