Document TX completion bug.

diff --git a/src/arch/i386/drivers/net/undinet.c b/src/arch/i386/drivers/net/undinet.c
index 6bc0fc3..0710659 100644 (file)
--- a/src/arch/i386/drivers/net/undinet.c
+++ b/src/arch/i386/drivers/net/undinet.c
@@ -333,6 +333,16 @@ static int undinet_transmit ( struct net_device *netdev,
        size_t len = iob_len ( iobuf );
        int rc;
 
+       /* Technically, we ought to make sure that the previous
+        * transmission has completed before we re-use the buffer.
+        * However, this would break a gPXE-running-over-Etherboot
+        * setup, since Etherboot fails to generate TX completions.
+        * In practice this won't be a problem, since our TX datapath
+        * has a very low packet volume and we can get away with
+        * assuming that a TX will be complete by the time we want to
+        * transmit the next packet.
+        */
+
        /* Copy packet to UNDI I/O buffer */
        if ( len > sizeof ( basemem_packet ) )
                len = sizeof ( basemem_packet );