diff --git a/gc_bba_test/source/tests.c b/gc_bba_test/source/tests.c
index 5e1f8bf..6e99cd9 100644
--- a/gc_bba_test/source/tests.c
+++ b/gc_bba_test/source/tests.c
@@ -343,20 +343,41 @@ static int t_rx(char *m, size_t n)
 
 static int t_dma(char *m, size_t n)
 {
-	u8 buf[64];
-	u32 dlen;
-	if (bba_stream(SPRAM_BASE, buf, sizeof(buf)) < 0) {
-		snprintf(m, n, "stream read failed"); return 1;
+	u8 buf[64], rp[2], wp[2];
+	u32 dlen, page, addr;
+	if (bba_read(REG_RRP_LO, rp, 2) < 0) { snprintf(m, n, "RRP read failed"); return 1; }
+	if (bba_read(REG_RWP_LO, wp, 2) < 0) { snprintf(m, n, "RWP read failed"); return 1; }
+	page = ((u32)rp[1] << 8) | rp[0];
+	/* RWP/RRP are PAGE pointers into the 15-page ring, so the next
+	 * unconsumed frame's descriptor is at RRP*256 -- NOT at SPRAM_BASE.
+	 * Reading 0x100 unconditionally only happens to work while nothing has
+	 * been consumed and the ring has not wrapped, which is why this test
+	 * reported "ring empty?" on a board that had just passed the RX test. */
+	if (rp[0] == wp[0] && rp[1] == wp[1]) {
+		snprintf(m, n, "ring empty: RRP==RWP==%u (send it a frame first)",
+		         (unsigned)page);
+		return 2;
+	}
+	if (page < 1 || page > 15) {
+		snprintf(m, n, "RRP page %u outside ring pages 1-15", (unsigned)page);
+		return 1;
+	}
+	addr = page << 8;
+	if (bba_stream((u16)addr, buf, sizeof(buf)) < 0) {
+		snprintf(m, n, "stream read at 0x%04X failed", (unsigned)addr);
+		return 1;
 	}
 	/* 4-byte ring descriptor; its length field INCLUDES the descriptor. */
 	dlen = ((u32)buf[2] << 8) | buf[3];
 	if (dlen > 4 && dlen <= 1518) {
-		snprintf(m, n, "descriptor len 0x%04X = %u frame bytes, etype %02X%02X",
-		         (unsigned)dlen, (unsigned)(dlen - 4), buf[16], buf[17]);
+		snprintf(m, n, "p%u len 0x%04X = %u bytes, etype %02X%02X",
+		         (unsigned)page, (unsigned)dlen, (unsigned)(dlen - 4),
+		         buf[16], buf[17]);
 		return 0;
 	}
-	snprintf(m, n, "descriptor len 0x%04X implausible (ring empty?)", (unsigned)dlen);
-	return 2;   /* skip rather than fail: needs a received frame first */
+	snprintf(m, n, "p%u len 0x%04X implausible (RWP=%u)", (unsigned)page,
+	         (unsigned)dlen, (unsigned)(((u32)wp[1] << 8) | wp[0]));
+	return 1;
 }
 
 static int t_dma_stream_len(char *m, size_t n)