36 lines
1.7 KiB
ReStructuredText
36 lines
1.7 KiB
ReStructuredText
|
.. _env_vars:
|
||
|
|
|
||
|
|
Environment Variables
|
||
|
|
======================
|
||
|
|
|
||
|
|
Certain environment variables can affect or tune the behavior of the
|
||
|
|
library. The variables and their behavior are described here.
|
||
|
|
|
||
|
|
* ``BOTAN_THREAD_POOL_SIZE`` controls the number of threads which will be
|
||
|
|
created for a thread pool used for some purposes within the library. If not
|
||
|
|
set, or set to 0, then it defaults to the number of CPUs available on the
|
||
|
|
system. If it is set to the string "none" then the thread pool is disabled;
|
||
|
|
instead all work passed to the thread pool will be executed immediately
|
||
|
|
by the calling thread.
|
||
|
|
|
||
|
|
As of version 3.2.0, on MinGW the thread pool is by default disabled, due to a
|
||
|
|
bug which causes deadlock on application shutdown. Enabling the pool can be
|
||
|
|
explicitly requested by setting ``BOTAN_THREAD_POOL_SIZE`` to an integer
|
||
|
|
value.
|
||
|
|
|
||
|
|
* ``BOTAN_MLOCK_POOL_SIZE`` controls the total amount of memory, in bytes, which
|
||
|
|
will be locked in memory using ``mlock`` or ``VirtualLock`` and managed in a
|
||
|
|
memory pool. This should be a multiple of the system page size. If set to
|
||
|
|
``0``, then the memory pool is disabled.
|
||
|
|
|
||
|
|
* ``BOTAN_FFI_PRINT_EXCEPTIONS`` if this variable is set (to any value), then
|
||
|
|
if an exception is caught by the FFI layer, before returning an error code, it
|
||
|
|
will print the text message of the exception to stderr. This is primarily
|
||
|
|
intended for debugging.
|
||
|
|
|
||
|
|
* ``BOTAN_CLEAR_CPUID``: this variable can be set to a comma-separated list of
|
||
|
|
CPUID fields to ignore. For example setting ``BOTAN_CLEAR_CPUID=avx2,avx512``
|
||
|
|
will cause AVX2 and AVX-512 codepaths to be avoided. Note that disabling basic
|
||
|
|
features (notably NEON or SSE2/SSSE3) can cause other higher level features
|
||
|
|
like AES-NI to also become disabled.
|