docs: explain SSTP transport selection at startup

Signed-off-by: Denys Fedoryshchenko <denys.f@collabora.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/README.md b/README.md
index f694338f..af678b9e 100644
--- a/README.md
+++ b/README.md
@@ -87,6 +87,12 @@ kernel:
       -DKDIR="/usr/src/linux-headers-$(uname -r)"
     cmake --build build
 
+For SSTP's optional PPPoSEQ transport, also set BUILD_PPPOSEQ_DRIVER=TRUE
+and install the ppposeq kernel module. SSTP tries to load it at startup;
+ppp-mode=auto uses it if available and otherwise selects async PPP.
+Changing [sstp] ppp-mode or switching from async to PPPoSEQ requires a daemon
+restart. See "man 5 accel-ppp.conf" for the transport options.
+
 
 Configuration
 =============
diff --git a/accel-pppd/accel-ppp.conf.5 b/accel-pppd/accel-ppp.conf.5
index eba8a39f..468c8d9a 100644
--- a/accel-pppd/accel-ppp.conf.5
+++ b/accel-pppd/accel-ppp.conf.5
@@ -1023,6 +1023,14 @@ HDLC framing is done in userspace.
 - use seqpacket if the module is available, otherwise async.
 .br
 Default is auto.
+.br
+The transport is selected at daemon startup. For auto or seqpacket, accel-ppp
+tries to load the ppposeq kernel module if it is not already available.
+Build and install that module with BUILD_PPPOSEQ_DRIVER=TRUE to enable it.
+The seqpacket mode requires the module; only auto falls back to async when
+it is unavailable. Changing ppp-mode, or making ppposeq available after auto
+has selected async, requires a daemon restart; configuration reload does not
+reselect the transport.
 .TP
 .BI "accept=" ssl,proxy
 Specifies incoming connection acceptance mode.