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Date: Thu, 03 May 2012 11:25:49 -0300
From: Claudio André <claudioandre.br@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: cryptsha512-opencl
Em 03-05-2012 07:59, magnum escreveu:
> Claudio,
>
> Do you think you can get it working on AMD soon too?
I saw a really crazy thing in 7970. For example:
The code:
output->v[3] = (i < rounds);
output->v[4] = (i >= rounds);
output->v[5] = rounds;
output->v[6] = i;
The output (after o loop, so "i" should be 4999 [decimal]):
Tahiti: 0000000000000000 0000000000000001 0000000000001388
0000000000000001 <==> (1 >= 5000)???????
CPU: 0000000000000001 0000000000000000 0000000000001388 0000000000001387
Trying some other tests, i found a condition where:
(i < rounds) == false AND (i >= rounds) == false
My understanding is that ((int + uint) + (maybe) local memory access) do
the trick. Not sure.
I don't want to create a kernel only to succeed on this crazy
environment. Trying to find a pattern.
> We might try to
> wrap up a Jumbo release soon. Also (or at the same time but this is
> lower prio) you might want to get rid of byte stores. The AMD will honor
> this setting:
>
> #ifdef cl_khr_byte_addressable_store
> #pragma OPENCL EXTENSION cl_khr_byte_addressable_store : disable
> #endif
>
> This will make your format fail until you have replaced all byte pointer
> writes to macros like the PUTCHAR one in rar (it's normally as simple as
> that). Note that besides making your format work on more devices, this
> will probably also speed things up.
>
> BTW, that pragma disable *should* work on nvidia too but they just
> silently ignore it.
>
> magnum
Will do it.
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