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diff --git a/doc/man3/OSSL_trace_set_channel.pod b/doc/man3/OSSL_trace_set_channel.pod
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+++ b/doc/man3/OSSL_trace_set_channel.pod
@@ -0,0 +1,332 @@
+=pod
+
+=for openssl foreign manual atexit(3)
+
+=head1 NAME
+
+OSSL_trace_set_channel, OSSL_trace_set_prefix, OSSL_trace_set_suffix,
+OSSL_trace_set_callback, OSSL_trace_cb - Enabling trace output
+
+=head1 SYNOPSIS
+
+ #include <openssl/trace.h>
+
+ typedef size_t (*OSSL_trace_cb)(const char *buf, size_t cnt,
+                                 int category, int cmd, void *data);
+
+ void OSSL_trace_set_channel(int category, BIO *bio);
+ void OSSL_trace_set_prefix(int category, const char *prefix);
+ void OSSL_trace_set_suffix(int category, const char *suffix);
+ void OSSL_trace_set_callback(int category, OSSL_trace_cb cb, void  *data);
+
+=head1 DESCRIPTION
+
+If available (see L</NOTES> below), the application can request
+internal trace output.
+This output comes in form of free text for humans to read.
+
+The trace output is divided into categories which can be
+enabled individually.
+Every category can be enabled individually by attaching a so called
+I<trace channel> to it, which in the simplest case is just a BIO object
+to which the application can write the tracing output for this category.
+Alternatively, the application can provide a tracer callback in order to
+get more finegrained trace information. This callback will be wrapped
+internally by a dedicated BIO object.
+
+For the tracing code, both trace channel types are indistinguishable.
+These are called a I<simple trace channel> and a I<callback trace channel>,
+respectively.
+
+=head2 Functions
+
+OSSL_trace_set_channel() is used to enable the given trace C<category>
+by attaching the B<BIO> I<bio> object as (simple) trace channel.
+On success the ownership of the BIO is transferred to the channel,
+so the caller must not free it directly.
+
+OSSL_trace_set_prefix() and OSSL_trace_set_suffix() can be used to add
+an extra line for each channel, to be output before and after group of
+tracing output.
+What constitues an output group is decided by the code that produces
+the output.
+The lines given here are considered immutable; for more dynamic
+tracing prefixes, consider setting a callback with
+OSSL_trace_set_callback() instead.
+
+OSSL_trace_set_callback() is used to enable the given trace
+I<category> by giving it the tracer callback I<cb> with the associated
+data I<data>, which will simply be passed through to I<cb> whenever
+it's called. The callback function is internally wrapped by a
+dedicated BIO object, the so called I<callback trace channel>.
+This should be used when it's desirable to do form the trace output to
+something suitable for application needs where a prefix and suffix
+line aren't enough.
+
+OSSL_trace_set_channel() and OSSL_trace_set_callback() are mutually
+exclusive, calling one of them will clear whatever was set by the
+previous call.
+
+Calling OSSL_trace_set_channel() with NULL for I<channel> or
+OSSL_trace_set_callback() with NULL for I<cb> disables tracing for
+the given I<category>.
+
+=head2 Trace callback
+
+The tracer callback must return a B<size_t>, which must be zero on
+error and otherwise return the number of bytes that were output.
+It receives a text buffer I<buf> with I<cnt> bytes of text, as well as
+the I<category>, a control number I<cmd>, and the I<data> that was
+passed to OSSL_trace_set_callback().
+
+The possible control numbers are:
+
+=over 4
+
+=item B<OSSL_TRACE_CTRL_BEGIN>
+
+The callback is called from OSSL_trace_begin(), which gives the
+callback the possibility to output a dynamic starting line, or set a
+prefix that should be output at the beginning of each line, or
+something other.
+
+=item B<OSSL_TRACE_CTRL_WRITE>
+
+This callback is called whenever data is written to the BIO by some
+regular BIO output routine.
+An arbitrary number of B<OSSL_TRACE_CTRL_WRITE> callbacks can occur
+inside a group marked by a pair of B<OSSL_TRACE_CTRL_BEGIN> and
+B<OSSL_TRACE_CTRL_END> calls, but never outside such a group.
+
+=item B<OSSL_TRACE_CTRL_END>
+
+The callback is called from OSSL_trace_end(), which gives the callback
+the possibility to output a dynamic ending line, or reset the line
+prefix that was set with B<OSSL_TRACE_CTRL_BEGIN>, or something other.
+
+=back
+
+=head2 Trace categories
+
+The trace categories are simple numbers available through macros.
+
+=over 4
+
+=item B<OSSL_TRACE_CATEGORY_TRACE>
+
+Traces the OpenSSL trace API itself.
+
+More precisely, this will generate trace output any time a new
+trace hook is set.
+
+=item B<OSSL_TRACE_CATEGORY_INIT>
+
+Traces OpenSSL library initialization and cleanup.
+
+This needs special care, as OpenSSL will do automatic cleanup after
+exit from C<main()>, and any tracing output done during this cleanup
+will be lost if the tracing channel or callback were cleaned away
+prematurely.
+A suggestion is to make such cleanup part of a function that's
+registered very early with L<atexit(3)>.
+
+=item B<OSSL_TRACE_CATEGORY_TLS>
+
+Traces the TLS/SSL protocol.
+
+=item B<OSSL_TRACE_CATEGORY_TLS_CIPHER>
+
+Traces the ciphers used by the TLS/SSL protocol.
+
+=item B<OSSL_TRACE_CATEGORY_CONF>
+
+Traces details about the provider and engine configuration.
+
+=item B<OSSL_TRACE_CATEGORY_ENGINE_TABLE>
+
+Traces the ENGINE algorithm table selection.
+
+More precisely, functions like ENGINE_get_pkey_asn1_meth_engine(),
+ENGINE_get_pkey_meth_engine(), ENGINE_get_cipher_engine(),
+ENGINE_get_digest_engine(), will generate trace summaries of the
+handling of internal tables.
+
+=item B<OSSL_TRACE_CATEGORY_ENGINE_REF_COUNT>
+
+Traces the ENGINE reference counting.
+
+More precisely, both reference counts in the ENGINE structure will be
+monitored with a line of trace output generated for each change.
+
+=item B<OSSL_TRACE_CATEGORY_PKCS5V2>
+
+Traces PKCS#5 v2 key generation.
+
+=item B<OSSL_TRACE_CATEGORY_PKCS12_KEYGEN>
+
+Traces PKCS#12 key generation.
+
+=item B<OSSL_TRACE_CATEGORY_PKCS12_DECRYPT>
+
+Traces PKCS#12 decryption.
+
+=item B<OSSL_TRACE_CATEGORY_X509V3_POLICY>
+
+Traces X509v3 policy processing.
+
+More precisely, this generates the complete policy tree at various
+point during evaluation.
+
+=item B<OSSL_TRACE_CATEGORY_BN_CTX>
+
+Traces BIGNUM context operations.
+
+=item B<OSSL_TRACE_CATEGORY_CMP>
+
+Traces CMP client and server activity.
+
+=item B<OSSL_TRACE_CATEGORY_STORE>
+
+Traces STORE operations.
+
+=item B<OSSL_TRACE_CATEGORY_DECODER>
+
+Traces decoder operations.
+
+=item B<OSSL_TRACE_CATEGORY_ENCODER>
+
+Traces encoder operations.
+
+=item B<OSSL_TRACE_CATEGORY_REF_COUNT>
+
+Traces decrementing certain ASN.1 structure references.
+
+=back
+
+There is also B<OSSL_TRACE_CATEGORY_ALL>, which works as a fallback
+and can be used to get I<all> trace output.
+
+Note, however, that in this case all trace output will effectively be
+associated with the 'ALL' category, which is undesirable if the
+application intends to include the category name in the trace output.
+In this case it is better to register separate channels for each
+trace category instead.
+
+=head1 RETURN VALUES
+
+OSSL_trace_set_channel(), OSSL_trace_set_prefix(),
+OSSL_trace_set_suffix(), and OSSL_trace_set_callback() return 1 on
+success, or 0 on failure.
+
+=head1 EXAMPLES
+
+In all examples below, the trace producing code is assumed to be
+the following:
+
+ int foo = 42;
+ const char bar[] = { 0,  1,  2,  3,  4,  5,  6,  7,
+                      8,  9, 10, 11, 12, 13, 14, 15 };
+
+ OSSL_TRACE_BEGIN(TLS) {
+     BIO_puts(trc_out, "foo: ");
+     BIO_printf(trc_out, "%d\n", foo);
+     BIO_dump(trc_out, bar, sizeof(bar));
+ } OSSL_TRACE_END(TLS);
+
+=head2 Simple example
+
+An example with just a channel and constant prefix / suffix.
+
+ int main(int argc, char *argv[])
+ {
+     BIO *err = BIO_new_fp(stderr, BIO_NOCLOSE | BIO_FP_TEXT);
+     OSSL_trace_set_channel(OSSL_TRACE_CATEGORY_SSL, err);
+     OSSL_trace_set_prefix(OSSL_TRACE_CATEGORY_SSL, "BEGIN TRACE[TLS]");
+     OSSL_trace_set_suffix(OSSL_TRACE_CATEGORY_SSL, "END TRACE[TLS]");
+
+     /* ... work ... */
+ }
+
+When the trace producing code above is performed, this will be output
+on standard error:
+
+ BEGIN TRACE[TLS]
+ foo: 42
+ 0000 - 00 01 02 03 04 05 06 07-08 09 0a 0b 0c 0d 0e 0f   ................
+ END TRACE[TLS]
+
+=head2 Advanced example
+
+This example uses the callback, and depends on pthreads functionality.
+
+ static size_t cb(const char *buf, size_t cnt,
+                 int category, int cmd, void *vdata)
+ {
+     BIO *bio = vdata;
+     const char *label = NULL;
+
+     switch (cmd) {
+     case OSSL_TRACE_CTRL_BEGIN:
+         label = "BEGIN";
+         break;
+     case OSSL_TRACE_CTRL_END:
+         label = "END";
+         break;
+     }
+
+     if (label != NULL) {
+         union {
+             pthread_t tid;
+             unsigned long ltid;
+         } tid;
+
+         tid.tid = pthread_self();
+         BIO_printf(bio, "%s TRACE[%s]:%lx\n",
+                    label, OSSL_trace_get_category_name(category), tid.ltid);
+     }
+     return (size_t)BIO_puts(bio, buf);
+ }
+
+ int main(int argc, char *argv[])
+ {
+     BIO *err = BIO_new_fp(stderr, BIO_NOCLOSE | BIO_FP_TEXT);
+     OSSL_trace_set_callback(OSSL_TRACE_CATEGORY_SSL, cb, err);
+
+     /* ... work ... */
+ }
+
+The output is almost the same as for the simple example above.
+
+ BEGIN TRACE[TLS]:7f9eb0193b80
+ foo: 42
+ 0000 - 00 01 02 03 04 05 06 07-08 09 0a 0b 0c 0d 0e 0f   ................
+ END TRACE[TLS]:7f9eb0193b80
+
+=head1 NOTES
+
+=head2 Configure Tracing
+
+By default, the OpenSSL library is built with tracing disabled. To
+use the tracing functionality documented here, it is therefore
+necessary to configure and build OpenSSL with the 'enable-trace' option.
+
+When the library is built with tracing disabled, the macro
+B<OPENSSL_NO_TRACE> is defined in F<< <openssl/opensslconf.h> >> and all
+functions described here are inoperational, i.e. will do nothing.
+
+=head1 HISTORY
+
+OSSL_trace_set_channel(), OSSL_trace_set_prefix(),
+OSSL_trace_set_suffix(), and OSSL_trace_set_callback() were all added
+in OpenSSL 3.0.
+
+=head1 COPYRIGHT
+
+Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the Apache License 2.0 (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut