[PATCH] arch/powerpc/lib/copy_32.S: Use alternate memcpy for MPC512x and MPC52xx

Grant Likely grant.likely at secretlab.ca
Thu Jul 8 15:38:12 EST 2010

On Wed, Jul 7, 2010 at 11:10 PM, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> On Tue, 2010-06-29 at 11:04 -0500, Steve Deiters wrote:
>> These processors will corrupt data if accessing the local bus with
>> unaligned
>> addresses. This version fixes the typical case of copying from Flash on
>> the
>> local bus by keeping the source address always aligned.
> Shouldn't this be solved by using memcpy_to/fromio ?

Maybe.  plain memcpy() access to anything localbus-attached on the
mpc5xxx is the wrong thing to do.  memcpy_to/fromio might do the right
thing; but the caller must understand the limitations of the localplus
bus.  The byte-wise alignment that memcpy_to/fromio() does may not
work (depending on configuration).

Steve, what code is doing a memcpy from flash?


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