+.. SPDX-License-Identifier: GPL-2.0
- The Spidernet Device Driver
- ===========================
+===========================
+The Spidernet Device Driver
+===========================
Written by Linas Vepstas <linas@austin.ibm.com>
of the ring, starting at the tail pointer, and listing the status
of the descrs that follow.
-A typical example of the output, for a nearly idle system, might be
+A typical example of the output, for a nearly idle system, might be::
-net eth1: Total number of descrs=256
-net eth1: Chain tail located at descr=20
-net eth1: Chain head is at 20
-net eth1: HW curr desc (GDACTDPA) is at 21
-net eth1: Have 1 descrs with stat=x40800101
-net eth1: HW next desc (GDACNEXTDA) is at 22
-net eth1: Last 255 descrs with stat=xa0800000
+ net eth1: Total number of descrs=256
+ net eth1: Chain tail located at descr=20
+ net eth1: Chain head is at 20
+ net eth1: HW curr desc (GDACTDPA) is at 21
+ net eth1: Have 1 descrs with stat=x40800101
+ net eth1: HW next desc (GDACNEXTDA) is at 22
+ net eth1: Last 255 descrs with stat=xa0800000
In the above, the hardware has filled in one descr, number 20. Both
head and tail are pointing at 20, because it has not yet been emptied.
to "empty". The actual value printed is RXCOMST_A.
In the device driver source code, a different set of names are
-used for these same concepts, so that
+used for these same concepts, so that::
-"empty" == SPIDER_NET_DESCR_CARDOWNED == 0xa
-"full" == SPIDER_NET_DESCR_FRAME_END == 0x4
-"not in use" == SPIDER_NET_DESCR_NOT_IN_USE == 0xf
+ "empty" == SPIDER_NET_DESCR_CARDOWNED == 0xa
+ "full" == SPIDER_NET_DESCR_FRAME_END == 0x4
+ "not in use" == SPIDER_NET_DESCR_NOT_IN_USE == 0xf
The RX RAM full bug/feature
empty.
A call to show_rx_chain() at this point indicates the nature of the
-problem. A typical print when the network is hung shows the following:
-
-net eth1: Spider RX RAM full, incoming packets might be discarded!
-net eth1: Total number of descrs=256
-net eth1: Chain tail located at descr=255
-net eth1: Chain head is at 255
-net eth1: HW curr desc (GDACTDPA) is at 0
-net eth1: Have 1 descrs with stat=xa0800000
-net eth1: HW next desc (GDACNEXTDA) is at 1
-net eth1: Have 127 descrs with stat=x40800101
-net eth1: Have 1 descrs with stat=x40800001
-net eth1: Have 126 descrs with stat=x40800101
-net eth1: Last 1 descrs with stat=xa0800000
+problem. A typical print when the network is hung shows the following::
+
+ net eth1: Spider RX RAM full, incoming packets might be discarded!
+ net eth1: Total number of descrs=256
+ net eth1: Chain tail located at descr=255
+ net eth1: Chain head is at 255
+ net eth1: HW curr desc (GDACTDPA) is at 0
+ net eth1: Have 1 descrs with stat=xa0800000
+ net eth1: HW next desc (GDACNEXTDA) is at 1
+ net eth1: Have 127 descrs with stat=x40800101
+ net eth1: Have 1 descrs with stat=x40800001
+ net eth1: Have 126 descrs with stat=x40800101
+ net eth1: Last 1 descrs with stat=xa0800000
Both the tail and head pointers are pointing at descr 255, which is
marked xa... which is "empty". Thus, from the OS point of view, there
of interrupts, about 1K/sec. For smaller packets, this will drop to zero
interrupts, as the hardware can empty the queue faster than the kernel
can fill it.
-
-
- ======= END OF DOCUMENT ========
-