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openssl/doc/crypto/OPENSSL_ia32cap.pod

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Add framework for yet another assembler module dubbed "cpuid." Idea is to have a placeholder to small routines, which can be written only in assembler. In IA-32 case this includes processor capability identification and access to Time-Stamp Counter. As discussed earlier OPENSSL_ia32cap is introduced to control recently added SSE2 code pathes (see docs/crypto/OPENSSL_ia32cap.pod). For the moment the code is operational on ELF platforms only. I haven't checked it yet, but I have all reasons to believe that Windows build should fail to link too. I'll be looking into it shortly...
2004-07-27 04:18:55 +08:00
=pod
=head1 NAME
The NAME section of a man page is required to have a dash followed by a short description, at least according to pod2man. PR: 1127
2005-06-24 05:45:37 +08:00
OPENSSL_ia32cap - finding the IA-32 processor capabilities
Add framework for yet another assembler module dubbed "cpuid." Idea is to have a placeholder to small routines, which can be written only in assembler. In IA-32 case this includes processor capability identification and access to Time-Stamp Counter. As discussed earlier OPENSSL_ia32cap is introduced to control recently added SSE2 code pathes (see docs/crypto/OPENSSL_ia32cap.pod). For the moment the code is operational on ELF platforms only. I haven't checked it yet, but I have all reasons to believe that Windows build should fail to link too. I'll be looking into it shortly...
2004-07-27 04:18:55 +08:00
=head1 SYNOPSIS
OPENSSL_ia32cap final touches. Note that OPENSSL_ia32cap is no longer a symbol, but a macro expanded as (*(OPENSSL_ia32cap_loc())). The latter is the only one to be exported to application.
2004-08-30 00:36:05 +08:00
unsigned long *OPENSSL_ia32cap_loc(void);
#define OPENSSL_ia32cap (*(OPENSSL_ia32cap_loc()))
Add framework for yet another assembler module dubbed "cpuid." Idea is to have a placeholder to small routines, which can be written only in assembler. In IA-32 case this includes processor capability identification and access to Time-Stamp Counter. As discussed earlier OPENSSL_ia32cap is introduced to control recently added SSE2 code pathes (see docs/crypto/OPENSSL_ia32cap.pod). For the moment the code is operational on ELF platforms only. I haven't checked it yet, but I have all reasons to believe that Windows build should fail to link too. I'll be looking into it shortly...
2004-07-27 04:18:55 +08:00
=head1 DESCRIPTION
OPENSSL_ia32cap final touches. Note that OPENSSL_ia32cap is no longer a symbol, but a macro expanded as (*(OPENSSL_ia32cap_loc())). The latter is the only one to be exported to application.
2004-08-30 00:36:05 +08:00
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
RC4 tune-up for Intel P4 core, both 32- and 64-bit ones. As it's apparently impossible to compose blended code with would perform satisfactory on all x86 and x86_64 cores, an extra RC4_CHAR code-path is introduced and P4 core is detected at run-time. This way we keep original performance on non-P4 implementations and turbo-charge P4 performance by factor of 2.8x (on 32-bit core).
2004-11-21 18:36:25 +08:00
Intel Application Note #241618). Naturally it's meaningful on IA-32[E]
OPENSSL_ia32cap final touches. Note that OPENSSL_ia32cap is no longer a symbol, but a macro expanded as (*(OPENSSL_ia32cap_loc())). The latter is the only one to be exported to application.
2004-08-30 00:36:05 +08:00
platforms only. The variable is normally set up automatically upon
toolkit initialization, but can be manipulated afterwards to modify
RC4 tune-up for Intel P4 core, both 32- and 64-bit ones. As it's apparently impossible to compose blended code with would perform satisfactory on all x86 and x86_64 cores, an extra RC4_CHAR code-path is introduced and P4 core is detected at run-time. This way we keep original performance on non-P4 implementations and turbo-charge P4 performance by factor of 2.8x (on 32-bit core).
2004-11-21 18:36:25 +08:00
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
OPENSSL_ia32cap final touches. Note that OPENSSL_ia32cap is no longer a symbol, but a macro expanded as (*(OPENSSL_ia32cap_loc())). The latter is the only one to be exported to application.
2004-08-30 00:36:05 +08:00
denoting presence of Time-Stamp Counter. Clearing bit #26 at run-time
for example disables high-performance SSE2 code present in the crypto
Add framework for yet another assembler module dubbed "cpuid." Idea is to have a placeholder to small routines, which can be written only in assembler. In IA-32 case this includes processor capability identification and access to Time-Stamp Counter. As discussed earlier OPENSSL_ia32cap is introduced to control recently added SSE2 code pathes (see docs/crypto/OPENSSL_ia32cap.pod). For the moment the code is operational on ELF platforms only. I haven't checked it yet, but I have all reasons to believe that Windows build should fail to link too. I'll be looking into it shortly...
2004-07-27 04:18:55 +08:00
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
OPENSSL_ia32cap final touches. Note that OPENSSL_ia32cap is no longer a symbol, but a macro expanded as (*(OPENSSL_ia32cap_loc())). The latter is the only one to be exported to application.
2004-08-30 00:36:05 +08:00
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
Add framework for yet another assembler module dubbed "cpuid." Idea is to have a placeholder to small routines, which can be written only in assembler. In IA-32 case this includes processor capability identification and access to Time-Stamp Counter. As discussed earlier OPENSSL_ia32cap is introduced to control recently added SSE2 code pathes (see docs/crypto/OPENSSL_ia32cap.pod). For the moment the code is operational on ELF platforms only. I haven't checked it yet, but I have all reasons to believe that Windows build should fail to link too. I'll be looking into it shortly...
2004-07-27 04:18:55 +08:00
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.
=cut
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