ethernet/toshiba/spider_net.rst

44 descriptor pointer (GDACTDPA). The GDACTDPA points at the descr
53 hardware is ahead, the tail pointer will be pointing at a "full"
63 When traffic is flowing, then the head pointer will be pointing at
71 pointer, at which point the OS will notice that the head descr is
75 all be pointing at the same descr, which should be "empty". All of the
80 of the ring, starting at the tail pointer, and listing the status
86     net eth1: Chain tail located at descr=20
87     net eth1: Chain head is at 20
88     net eth1: HW curr desc (GDACTDPA) is at 21
90     net eth1: HW next desc (GDACNEXTDA) is at 22
94 head and tail are pointing at 20, because it has not yet been emptied.
95 Meanwhile, hw is pointing at 21, which is free.
97 The "Have nnn decrs" refers to the descr starting at the tail: in this
98 case, nnn=1 descr, starting at descr 20. The "Last nnn descrs" refers
116 As long as the OS can empty out the RX buffers at a rate faster than
131 descriptor is invalid, it will not restart at that descriptor; instead
132 it will restart at the next descr. This potentially will lead to a
133 deadlock condition, as the tail pointer will be pointing at this descr,
141 A call to show_rx_chain() at this point indicates the nature of the
146     net eth1: Chain tail located at descr=255
147     net eth1: Chain head is at 255
148     net eth1: HW curr desc (GDACTDPA) is at 0
150     net eth1: HW next desc (GDACNEXTDA) is at 1
156 Both the tail and head pointers are pointing at descr 255, which is
163 The HW pointer is at descr 0. This descr is marked 0x4.. or "full".
167 descr 254, since tail was at 255.) Thus, the system is deadlocked,