git: 6fd3288c39c4 - main - thr_new.2: document THR_C_RUNTIME

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=6fd3288c39c493c4f252b715e8354e0d27d5ef90

commit 6fd3288c39c493c4f252b715e8354e0d27d5ef90
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-05-30 18:31:57 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-05-31 14:55:24 +0000

    thr_new.2: document THR_C_RUNTIME
    
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
---
 lib/libsys/thr_new.2 | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/libsys/thr_new.2 b/lib/libsys/thr_new.2
index c0bcc8bbc7c2..a04327723c34 100644
--- a/lib/libsys/thr_new.2
+++ b/lib/libsys/thr_new.2
@@ -133,6 +133,15 @@ The flag is not currently implemented.
 .It Dv THR_SYSTEM_SCOPE
 Create the system scope thread.
 The flag is not currently implemented.
+.It Dv THR_C_RUNTIME
+Indicate that the new thread is created by the C language runtime.
+It has architecture-specific meaning.
+.Pp
+On amd64, the flag requests that the specified
+.Fa tls_base
+was loaded into the
+.Va %fsbase
+register before calling a signal handler.
 .El
 .It Va rtp
 Real-time scheduling priority for the new thread.