Date: Wed, 21 Nov 2012 18:48:07 +0100 From: magnum <john.magnum@...hmail.com> To: john-dev@...ts.openwall.com Subject: Re: Problems on recent AMD driver On 21 Nov, 2012, at 18:06 , Claudio André <claudioandre.br@...il.com> wrote: > Em 21-11-2012 12:57, Claudio André escreveu: >> Em 20-11-2012 19:19, magnum escreveu: >>> If someone could review commit 1bee9a4 *very* closely, looking for violations of the specifications, problematic casts, misalignment or whatever, there's a chance you'll find something that solves this for all of the formats. But first, of course, confirm my assumption that md5crypt-opencl worked prior to that commit. >> > > I sent you a "pull request". Please, take a look. > > Claudio Thanks a lot for looking into this! So it seems what trips the segfault is the use of MEM_ALLOC_HOST_PTR, and mapping GPU memory to host memory. While dropping that will not make a lot of difference for md5crypt, it will mean a terrible performance drop for ntlmv2. The way I use it is by the [nvidia] book, for enabling best speed transfers or even zero-copy when possible. Also, why does it work here: magnum@...r-osx:src [unstable-jumbo]$ git grep -hC5 clEnqueueMapBuffer opencl_cryptsha256_fmt.c | head pinned_saved_keys = clCreateBuffer(context[ocl_gpu_id], CL_MEM_READ_WRITE | CL_MEM_ALLOC_HOST_PTR, sizeof(sha256_password) * gws, NULL, &ret_code); HANDLE_CLERROR(ret_code, "Error creating page-locked memory pinned_saved_keys"); plaintext = (sha256_password *) clEnqueueMapBuffer(queue[ocl_gpu_id], pinned_saved_keys, CL_TRUE, CL_MAP_WRITE | CL_MAP_READ, 0, sizeof(sha256_password) * gws, 0, NULL, NULL, &ret_code); HANDLE_CLERROR(ret_code, "Error mapping page-locked memory saved_plain"); The only difference I can see is that I use CL_MEM_READ_ONLY instead of CL_MEM_READ_WRITE. What happens if you revert to unstable-jumbo and just change that? magnum
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