[M] Change in osmo-trx[master]: libosmo-trx/trxd: support NOPE.{ind,req} in TRXDv0/v1 PDUs - gerrit-log

28 Jul 2026

fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-trx/+/43105?usp=email )
Change subject: libosmo-trx/trxd: support NOPE.{ind,req} in TRXDv0/v1 PDUs
......................................................................
libosmo-trx/trxd: support NOPE.{ind,req} in TRXDv0/v1 PDUs
TRXDv0 (and TRXDv1 in the downlink direction) has no MTS field, but
NOPE indications/requests do exist there in practice: the burst payload
is simply omitted, i.e. a header-only PDU.  This is how osmocom-bb's
trxcon transmits NOPE.req (see trx_if_handle_phyif_burst_req()).
Change-Id: I1a59f31d0f00c8509a016dc2bac71b6aa467f3a4
---
M libosmo-trx/include/osmocom/trx/trxd.h
M libosmo-trx/src/trxd.c
M tests/libosmo-trx/trxd_test.c
M tests/libosmo-trx/trxd_test.ok
4 files changed, 73 insertions(+), 18 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-trx refs/changes/05/43105/1

diff --git a/libosmo-trx/include/osmocom/trx/trxd.h b/libosmo-trx/include/osmocom/trx/trxd.h
index 9ed8275..d9e1632 100644
--- a/libosmo-trx/include/osmocom/trx/trxd.h
+++ b/libosmo-trx/include/osmocom/trx/trxd.h
@@ -38,6 +38,8 @@
/* Presence/meta flags for osmo_trxd_burst_{ind,req} */
 #define OSMO_TRXD_F_NOPE_IND	(1 << 0) /*!< no burst detected / idle indication */
+/*! alias of OSMO_TRXD_F_NOPE_IND, reading cleaner in BURST.req context */
+#define OSMO_TRXD_F_NOPE_REQ	OSMO_TRXD_F_NOPE_IND
 #define OSMO_TRXD_F_MOD_TYPE	(1 << 1) /*!< 'mod' is valid */
 #define OSMO_TRXD_F_TS_INFO	(1 << 2) /*!< 'tsc_set'/'tsc' are valid */
 #define OSMO_TRXD_F_CI_CB	(1 << 3) /*!< 'ci_cb' is valid */
diff --git a/libosmo-trx/src/trxd.c b/libosmo-trx/src/trxd.c
index d8c6a89..e3b51c4 100644
--- a/libosmo-trx/src/trxd.c
+++ b/libosmo-trx/src/trxd.c
@@ -211,6 +211,12 @@
trxd_burst_ind_parse_hdr_v0(bi, buf);
+	/* NOPE.ind: TRXDv0 has no MTS, the burst payload is simply omitted */
+	if (burst_len == 0) {
+		bi->flags |= OSMO_TRXD_F_NOPE_IND;
+		return buf_len;
+	}
+
    switch (burst_len) {
    case OSMO_TRXD_BURST_LEN_GMSK:
    case OSMO_TRXD_BURST_LEN_GMSK + 2:
@@ -383,9 +389,9 @@
  *  \param[inout] msg destination message buffer
  *  \param[in] pdu_ver TRXD PDU version to encode
  *  \param[in] bi burst indication to be encoded
- *  \returns 0 on success; negative on error.  Note that TRXDv0 cannot
- *	     carry NOPE.ind PDUs: -ENOTSUP is returned and the caller
- *	     shall skip (not send) them. */
+ *  \returns 0 on success; negative on error.  Note that TRXDv0 has no
+ *	     MTS field, so a NOPE.ind is encoded as a header-only PDU
+ *	     with the burst payload omitted. */
 int osmo_trxd_burst_ind_build(struct msgb *msg, uint8_t pdu_ver,
    		      const struct osmo_trxd_burst_ind *bi)
 {
@@ -395,9 +401,6 @@
switch (pdu_ver) {
    case 0:
-		/* v0 doesn't support NOPE.ind, the caller shall skip it */
-		if (bi->flags & OSMO_TRXD_F_NOPE_IND)
-			return -ENOTSUP;
    	buf = msgb_put(msg, TRXD_IND_V0HDR_LEN);
    	buf[0] = ((pdu_ver & 0x0f) << 4) | (bi->tn & 0x07);
    	osmo_store32be(bi->fn, buf + 1);
@@ -461,6 +464,12 @@
    br->fn = osmo_load32be(&buf[1]);
    br->att = buf[5];
+	/* NOPE.req: TRXDv0/v1 have no MTS, the burst payload is simply omitted */
+	if (burst_len == 0) {
+		br->flags |= OSMO_TRXD_F_NOPE_REQ;
+		return buf_len;
+	}
+
    switch (burst_len) {
    case OSMO_TRXD_BURST_LEN_8PSK:
    	br->mod = OSMO_TRXD_MOD_T_8PSK;
@@ -514,6 +523,12 @@
    	br->fn = st->fn;
    }
+	/* NOPE.req contains no burst */
+	if (br->flags & OSMO_TRXD_F_NOPE_REQ) {
+		br->burst_len = 0;
+		return hdr_len;
+	}
+
    burst_len = burst_len_by_mod(br->mod);
    if (burst_len < 0)
    	return burst_len;
@@ -630,9 +645,11 @@
    	return -ENOTSUP;
    }
-	/* copy hard-bits {0,1} */
-	memcpy(msgb_put(msg, br->burst_len),
-	       &br->burst[0], br->burst_len);
+	if (~br->flags & OSMO_TRXD_F_NOPE_REQ) {
+		/* copy hard-bits {0,1} */
+		memcpy(msgb_put(msg, br->burst_len),
+		       &br->burst[0], br->burst_len);
+	}
return 0;
 }
@@ -684,9 +701,13 @@
    static __thread char buf[256];
    struct osmo_strbuf sb = { .buf = buf, .len = sizeof(buf) };
-	OSMO_STRBUF_PRINTF(sb, "BURST.req tn=%u fn=%u att=%u", br->tn, br->fn, br->att);
+	OSMO_STRBUF_PRINTF(sb, "%s tn=%u fn=%u att=%u",
+			   (br->flags & OSMO_TRXD_F_NOPE_REQ) ? "NOPE.req" : "BURST.req",
+			   br->tn, br->fn, br->att);
    if (br->flags & OSMO_TRXD_F_TRX_NUM)
    	OSMO_STRBUF_PRINTF(sb, " trx_num=%u", br->trx_num);
+	if (br->flags & OSMO_TRXD_F_NOPE_REQ)
+		return buf;
    if (br->flags & OSMO_TRXD_F_MOD_TYPE)
    	OSMO_STRBUF_PRINTF(sb, " mod=%s", osmo_trxd_mod_type_name(br->mod));
    if (br->flags & OSMO_TRXD_F_TS_INFO)
diff --git a/tests/libosmo-trx/trxd_test.c b/tests/libosmo-trx/trxd_test.c
index 7cb3d94..d19c88c 100644
--- a/tests/libosmo-trx/trxd_test.c
+++ b/tests/libosmo-trx/trxd_test.c
@@ -124,13 +124,6 @@
    bi.flags = OSMO_TRXD_F_NOPE_IND | OSMO_TRXD_F_CI_CB;
rc = osmo_trxd_burst_ind_build(msg, pdu_ver, &bi);
-	if (pdu_ver == 0) {
-		/* TRXDv0 cannot carry NOPE.ind */
-		printf("build: rc=%d (expected -ENOTSUP)\n", rc);
-		OSMO_ASSERT(rc == -ENOTSUP);
-		msgb_free(msg);
-		return;
-	}
    OSMO_ASSERT(rc == 0);
    osmo_trxd_build_fin(msg, pdu_ver);
    printf("build: %s\n", osmo_trxd_burst_ind_name(&bi));
@@ -259,6 +252,34 @@
    msgb_free(msg);
 }
+static void test_burst_req_nope(uint8_t pdu_ver)
+{
+	struct osmo_trxd_parse_state st;
+	struct osmo_trxd_burst_req br, br2;
+	struct msgb *msg = msgb_alloc(4096, "nope");
+	int rc;
+
+	printf("=== %s(v%u) ===\n", __func__, pdu_ver);
+
+	fill_burst_req(&br, 0);
+	br.flags = OSMO_TRXD_F_NOPE_REQ;
+
+	rc = osmo_trxd_burst_req_build(msg, pdu_ver, &br);
+	OSMO_ASSERT(rc == 0);
+	osmo_trxd_build_fin(msg, pdu_ver);
+	printf("build: %s\n", osmo_trxd_burst_req_name(&br));
+
+	osmo_trxd_parse_state_init(&st);
+	rc = osmo_trxd_burst_req_parse(&st, &br2, msgb_data(msg), msgb_length(msg));
+	OSMO_ASSERT(rc == (int)msgb_length(msg));
+	printf("parse: %s\n", osmo_trxd_burst_req_name(&br2));
+
+	OSMO_ASSERT(br2.flags & OSMO_TRXD_F_NOPE_REQ);
+	OSMO_ASSERT(br2.burst_len == 0);
+
+	msgb_free(msg);
+}
+
 static void test_burst_req_batch(uint8_t pdu_ver)
 {
    struct osmo_trxd_parse_state st;
@@ -389,6 +410,7 @@
    for (uint8_t pdu_ver = 0; pdu_ver <= OSMO_TRXD_PDU_VER_MAX; pdu_ver++) {
    	test_burst_req(pdu_ver, OSMO_TRXD_BURST_LEN_GMSK);
    	test_burst_req(pdu_ver, OSMO_TRXD_BURST_LEN_8PSK);
+		test_burst_req_nope(pdu_ver);
    	test_burst_req_batch(pdu_ver);
test_burst_ind(pdu_ver, OSMO_TRXD_BURST_LEN_GMSK);
diff --git a/tests/libosmo-trx/trxd_test.ok b/tests/libosmo-trx/trxd_test.ok
index e4f22da..963322b 100644
--- a/tests/libosmo-trx/trxd_test.ok
+++ b/tests/libosmo-trx/trxd_test.ok
@@ -6,6 +6,9 @@
 build: BURST.req tn=2 fn=2654321 att=10 mod=8-PSK set=0 tsc=3 burst_len=444
 datagram (450 bytes): 02002880710a00010001000100010001...
 parse: BURST.req tn=2 fn=2654321 att=10 mod=8-PSK burst_len=444
+=== test_burst_req_nope(v0) ===
+build: NOPE.req tn=2 fn=2654321 att=10
+parse: NOPE.req tn=2 fn=2654321 att=10
 === test_burst_ind(v0, burst_len=148) ===
 build: BURST.ind tn=5 fn=1234567 rssi=-63 toa256=-512 C/I=-150 cB mod=GMSK set=1 tsc=7 burst_len=148
 datagram (156 bytes): 050012d6873ffe001be31be31be31be3...
@@ -15,7 +18,8 @@
 datagram (452 bytes): 050012d6873ffe001be31be31be31be3...
 parse: BURST.ind tn=5 fn=1234567 rssi=-63 toa256=-512 mod=8-PSK burst_len=444
 === test_burst_ind_nope(v0) ===
-build: rc=-95 (expected -ENOTSUP)
+build: NOPE.ind tn=5 fn=1234567 rssi=-63 toa256=-512 C/I=-150 cB
+parse: NOPE.ind tn=5 fn=1234567 rssi=-63 toa256=-512
 === test_burst_req(v1, burst_len=148) ===
 build: BURST.req tn=2 fn=2654321 att=10 mod=GMSK set=0 tsc=3 burst_len=148
 datagram (154 bytes): 12002880710a00010001000100010001...
@@ -24,6 +28,9 @@
 build: BURST.req tn=2 fn=2654321 att=10 mod=8-PSK set=0 tsc=3 burst_len=444
 datagram (450 bytes): 12002880710a00010001000100010001...
 parse: BURST.req tn=2 fn=2654321 att=10 mod=8-PSK burst_len=444
+=== test_burst_req_nope(v1) ===
+build: NOPE.req tn=2 fn=2654321 att=10
+parse: NOPE.req tn=2 fn=2654321 att=10
 === test_burst_ind(v1, burst_len=148) ===
 build: BURST.ind tn=5 fn=1234567 rssi=-63 toa256=-512 C/I=-150 cB mod=GMSK set=1 tsc=7 burst_len=148
 datagram (159 bytes): 150012d6873ffe000fff6a1be31be31b...
@@ -43,6 +50,9 @@
 build: BURST.req tn=2 fn=2654321 att=10 mod=8-PSK set=0 tsc=3 burst_len=444
 datagram (456 bytes): 2200230a000000000028807100010001...
 parse: BURST.req tn=2 fn=2654321 att=10 trx_num=0 mod=8-PSK set=0 tsc=3 burst_len=444
+=== test_burst_req_nope(v2) ===
+build: NOPE.req tn=2 fn=2654321 att=10
+parse: NOPE.req tn=2 fn=2654321 att=10 trx_num=0
 === test_burst_req_batch(v2) ===
 datagram (472 bytes)
 parse[0]: BURST.req tn=0 fn=2654321 att=10 trx_num=0 mod=GMSK set=0 tsc=3 burst_len=148
-- 
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Gerrit-MessageType: newchange
Gerrit-Project: osmo-trx
Gerrit-Branch: master
Gerrit-Change-Id: I1a59f31d0f00c8509a016dc2bac71b6aa467f3a4
Gerrit-Change-Number: 43105
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria vyanitskiy@sysmocom.de



    