Lack of documentation for OPENSSL_ia32cap_P
Jan Just Keijser
janjust at nikhef.nl
Sat Jul 25 23:56:10 UTC 2020
On 23/07/20 02:35, Jakob Bohm via openssl-users wrote:
> The OPENSSL_ia32cap_P variable, its bitfields and the code that sets
> it (in assembler) seemto have no clear documentation.
> Looking at x86_64cpuid.pl, I see jumps to ".Lintel" etc. being
> on stuff other than the CPU being an Intel CPU, while the code in
> there is
> generally unreadable due to the backwards SCO assembler format and the
> of clear comments about register usage such as "Here, EDX holds XXX
> and ESI
> holds YYYY" or eventhe code rationale "P50 microarchitecture stepping A
> incorrectly implements FDIV, so clear out private bit for using that in
> bignum implementations"
> As there is an external interface for changing the variable via an
> var, the lack of documentation makes that useless except for "cargo-cult"
> copying of values from old mailing list posts.
in the openssl 1.1.1g tree there's a file 'doc/man3/OPENSSL_ia32cap.pod'
which documents it a little - not sure if that is still up-to-date though...
More information about the openssl-users