Re: aoe fails on sparc64

[Ed L Cashin]

"David S. Miller" <davem@xxxxxxxxxxxxx> writes:

> From: Ed L Cashin <ecashin@xxxxxxxxxx>
> Date: Mon, 19 Sep 2005 10:24:00 -0400
>
>>   1) Passing le64_to_cpup an unaligned pointer is "OK" and within the
>>      intended use of the function.  I'm having trouble finding whether
>>      this is documented somewhere.
>> 
>>   2) These new changes to the sparc64 unaligned access fault handling
>>      will make it OK to leave the aoe driver the way it is in the
>>      mainline kernel.
>
> Both #1 and #2 are true.

That's interesting.  I think I'll send a patch documenting #1.

> Although it's very much discouraged to dereference unaligned pointers,
> especially in performance critical code (which this AOE case is not,
> thankfully), because performance will be really bad as the trap
> handler has to fix up the access on RISC platforms.

Yes, this only happens when per AoE device when the AoE device is
discovered.  Still, I might submit a patch that reverts the aoe driver
to getting the ATA identify values byte by byte as it used to do.

-- 
  Ed L Cashin <ecashin@xxxxxxxxxx>

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