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Date: Thu, 30 Oct 2014 15:40:51 +0100
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: "Failed copy data to gpu" when using fork with descrypt-opencl

On 2014-10-10 09:58, Royce Williams wrote:
> I'm getting the following error when I try to use fork to get more
> CPU cores participating in feeding my GPU:
>
> /srv/crack/john-latest/run/john --format=descrypt-opencl --fork=2
> ./badcrypt.test
> Device 0: GeForce GTX 970
> Local worksize (LWS) 64, Global worksize (GWS) 16384
> Loaded 1 password hash (descrypt-opencl, traditional crypt(3) [DES OpenCL])
> Node numbers 1-2 of 2 (fork)
> OpenCL error (CL_INVALID_COMMAND_QUEUE) in file
> (opencl_DES_bs_b_plug.c) at line (637) - (Failed Copy data to gpu)
> OpenCL error (CL_OUT_OF_RESOURCES) in file (opencl_DES_bs_b_plug.c) at
> line (637) - (Failed Copy data to gpu)

I should have catched this little detail earlier but you actually gave 
the wrong syntax, as it was. Maybe it wasn't very clear but at the time, 
README-OPENCL stated ``...For this to happen, the "-dev" option 
(--device) is mandatory┬┤┬┤. Just adding a -dev=0 or -dev=gpu should make 
your command line work with that commit.

Of course it did not fail in a good way: It should have worked in some 
sense (with a warning), or just bailed out. I have now committed a fix 
so this situation gets an implicit "--device=all". In many cases that is 
not what you really want (eg. it includes CPU devices) so you should 
probably learn to always use --dev=gpu when using --fork anyway.

Using -fork=4 on a quadcore+HT and GTX980 I got over 82 Mc/s.

magnum


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