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Date: Mon, 21 Oct 2013 00:50:45 +0200
From: magnum <john.magnum@...hmail.com>
To: "john-dev@...ts.openwall.com" <john-dev@...ts.openwall.com>
Subject: Bad version of Intel OpenCL CPU driver

This is Intel's CPU driver currently installed in Well:

Platform #1 name: Intel(R) OpenCL
Platform version: OpenCL 1.2 LINUX
         Device #0 (4) name:     Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
         Device vendor:          Intel(R) Corporation
         Device type:            CPU (LE)
         Device version:         OpenCL 1.2 (Build 67279)
         Driver version:         1.2
         Native vector widths:   char 32, short 16, int 8, long 8
         Preferred vector width: char 1, short 1, int 1, long 1
         Global Memory:          31.0 GB
         Global Memory Cache:    256.2 KB
         Local Memory:           32.0 KB (Global)
         Max memory alloc. size: 7.0 GB
         Max clock (MHz) :       4294970796
         Max Work Group Size:    1024
         Parallel compute cores: 8

Apparently this CPU is clocked at four peta-hertz, wow. That is just the 
first sign of how poor this driver is. Here's an example of trying to 
use it with phpass-opencl:

Device 4: Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
Stack dump:
0.      :73:13 <Spelling=:22:49>: current parser token ')'
1.      :64:1: parsing function body 'md5'
2.      :64:1: in compound statement ('{}')
Segmentation fault (core dumped)

It dies from this statement in line 73 of phpass kernel:
         a = ROTATE_LEFT(a, S11);

...and ROTATE_LEFT is defined in line 22:
#define ROTATE_LEFT(x, s)       rotate(x,(uint)s)

Wat. It's not even complicated code at all. I get similar problems all 
the time. This driver is even crappier than Apple's nvidia driver and I 
thought noone would ever beat that record.

magnum

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