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Under GNU General Public License
2012-05-24 22:12 @38.107.179.239 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
OPENSSL_ia32cap(3SSL) OpenSSL OPENSSL_ia32cap(3SSL)
NAME
OPENSSL_ia32cap - finding the IA-32 processor capabilities
SYNOPSIS
unsigned long *OPENSSL_ia32cap_loc(void);
#define OPENSSL_ia32cap (*(OPENSSL_ia32cap_loc()))
DESCRIPTION
Value returned by OPENSSL_ia32cap_loc() is address of a variable containing IA-32
processor capabilities bit vector as it appears in EDX register after executing CPUID
instruction with EAX=1 input value (see Intel Application Note #241618). Naturally it's
meaningful on IA-32[E] platforms only. The variable is normally set up automatically upon
toolkit initialization, but can be manipulated afterwards to modify crypto library
behaviour. For the moment of this writing three bits are significant, namely bit #28
denoting Hyperthreading, which is used to distinguish Intel P4 core, bit #26 denoting SSE2
support, and bit #4 denoting presence of Time-Stamp Counter. Clearing bit #26 at run-time
for example disables high-performance SSE2 code present in the crypto library. You might
have to do this if target OpenSSL application is executed on SSE2 capable CPU, but under
control of OS which does not support SSE2 extentions. Even though you can manipulate the
value programmatically, you most likely will find it more appropriate to set up an
environment variable with the same name prior starting target application, e.g. 'env
OPENSSL_ia32cap=0x10 apps/openssl', to achieve same effect without modifying the
application source code. Alternatively you can reconfigure the toolkit with no-sse2
option and recompile.
0.9.8g 2005-06-23 OPENSSL_ia32cap(3SSL)
Generated by $Id: phpMan.php,v 4.49 2006/02/26 13:18:18 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2012-05-24 22:12 @38.107.179.239 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)