doc/notes.org

   1 * uboot settings
   2
   3  set ipaddr 192.168.2.3
   4  set netmask 255.255.255.0
   5  set serverip 192.168.2.2
   6  set imagefile ryu/uImage
   7  set devicetreefile ryu/shark-ryu.dtb
   8  set nfspath /srv/nfs/root-shark
   9  set bootcmd_tftpnfs_static 'tftp 800000 ${imagefile}; tftp 7f0000 ${devicetreefile}; set bootargs ${linux_console} root=/dev/nfs nfsroot=${serverip}:${nfspath} rw ip=${ipaddr}; mw f0000b00 ${psc_cfg}; bootm 800000 - 7f0000'
  10  set bootcmd 'run bootcmd_tftpnfs_static'
  11
  12 * Questions
  13 ** Why crc modification alone does not produce an error and is not returned by cangw -L?
  14 * Kernel oops
  15 ** Linux-2.6.33.7-00005-ge2f49b5
  16 Unable to handle kernel paging request for instruction fetch
  17 Faulting instruction address: 0x8d56acc4
  18 Oops: Kernel access of bad area, sig: 11 [#1]
  19 PREEMPT Shark
  20 Modules linked in:
  21 NIP: 8d56acc4 LR: c0260208 CTR: 8d56acc7
  22 REGS: c03f3bc0 TRAP: 0400   Not tainted  (2.6.33.7-00005-ge2f49b5)
  23 MSR: 20009032 <EE,ME,IR,DR>  CR: 24008028  XER: 0000005f
  24 TASK = c03d5478[0] 'swapper' THREAD: c03f2000
  25 GPR00: 8d56acc7 c03f3c70 c03d5478 c7990160 c78d54ad 00000048 c79901a4 00000002
  26 GPR08: 000000e0 00000000 00000001 00000002 44000022 7f33ff4e 80000000 00000042
  27 GPR16: 00000008 20000000 c909e900 00000001 c03f3d78 c79326e0 00000008 c799dc1c
  28 GPR24: c7976800 c78d54f9 c7949828 c7a06620 c03f2000 c7990160 c78d54ad c03f3c70
  29 NIP [8d56acc4] 0x8d56acc4
  30 LR [c0260208] dev_queue_xmit+0x2f0/0x588
  31 Call Trace:
  32 [c03f3c70] [c025ff74] dev_queue_xmit+0x5c/0x588 (unreliable)
  33 [c03f3ca0] [c02d62d8] can_send+0x9c/0x1a0
  34 [c03f3cc0] [c02d97a8] can_can_gw_rcv+0x108/0x164
  35 [c03f3cf0] [c02d52ac] can_rcv_filter+0x240/0x2e8
  36 [c03f3d10] [c02d541c] can_rcv+0xc8/0x140
  37 [c03f3d30] [c025e968] netif_receive_skb+0x2ac/0x350
  38 [c03f3d70] [c020a230] mscan_rx_poll+0x1c0/0x464
  39 [c03f3dd0] [c025f428] net_rx_action+0x104/0x22c
  40 [c03f3e20] [c00345e0] __do_softirq+0x10c/0x21c
  41 [c03f3e70] [c00075d0] do_softirq+0x58/0x74
  42 [c03f3e80] [c0034300] irq_exit+0x8c/0xbc
  43 [c03f3e90] [c00076c8] do_IRQ+0xdc/0x188
  44 [c03f3ec0] [c0014db0] ret_from_except+0x0/0x14
  45 --- Exception: 501 at cpu_idle+0x104/0x114
  46     LR = cpu_idle+0x104/0x114
  47 [c03f3f80] [c000aefc] cpu_idle+0x68/0x114 (unreliable)
  48 [c03f3fa0] [c0003f40] rest_init+0xa4/0xc4
  49 [c03f3fc0] [c039f918] start_kernel+0x2e4/0x2fc
  50 [c03f3ff0] [00003438] 0x3438
  51 Instruction dump:
  52 XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
  53 XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
  54 Kernel panic - not syncing: Fatal exception in interrupt
  55 Call Trace:
  56 [c03f3ab0] [c0009cdc] show_stack+0x70/0x1d4 (unreliable)
  57 [c03f3b00] [c02ff5ec] dump_stack+0x2c/0x44
  58 [c03f3b10] [c02ff6b0] panic+0xac/0x19c
  59 [c03f3b60] [c0011df8] die+0x188/0x1a4
  60 [c03f3b90] [c00165c8] bad_page_fault+0x90/0xe0
  61 [c03f3bb0] [c0014bb8] handle_page_fault+0x7c/0x80
  62 --- Exception: 400 at 0x8d56acc4
  63     LR = dev_queue_xmit+0x2f0/0x588
  64 [c03f3c70] [c025ff74] dev_queue_xmit+0x5c/0x588 (unreliable)
  65 [c03f3ca0] [c02d62d8] can_send+0x9c/0x1a0
  66 [c03f3cc0] [c02d97a8] can_can_gw_rcv+0x108/0x164
  67 [c03f3cf0] [c02d52ac] can_rcv_filter+0x240/0x2e8
  68 [c03f3d10] [c02d541c] can_rcv+0xc8/0x140
  69 [c03f3d30] [c025e968] netif_receive_skb+0x2ac/0x350
  70 [c03f3d70] [c020a230] mscan_rx_poll+0x1c0/0x464
  71 [c03f3dd0] [c025f428] net_rx_action+0x104/0x22c
  72 [c03f3e20] [c00345e0] __do_softirq+0x10c/0x21c
  73 [c03f3e70] [c00075d0] do_softirq+0x58/0x74
  74 [c03f3e80] [c0034300] irq_exit+0x8c/0xbc
  75 [c03f3e90] [c00076c8] do_IRQ+0xdc/0x188
  76 [c03f3ec0] [c0014db0] ret_from_except+0x0/0x14
  77 --- Exception: 501 at cpu_idle+0x104/0x114
  78     LR = cpu_idle+0x104/0x114
  79 [c03f3f80] [c000aefc] cpu_idle+0x68/0x114 (unreliable)
  80 [c03f3fa0] [c0003f40] rest_init+0xa4/0xc4
  81 [c03f3fc0] [c039f918] start_kernel+0x2e4/0x2fc
  82 [c03f3ff0] [00003438] 0x3438
  83 Rebooting in 180 seconds..
  84
  85 * write returns ENOBUFS
  86 The reason is queuing discipline - the queue is full and
  87 pfifo_fast_enqueue returns failure. This failure is propagated down to
  88 qdisc_enqueue_root(), __dev_xmit_skb(), dev_queue_xmit() and
  89 can_send()
  90
  91 ** See the follwing trace
  92
  93 # tracer: function_graph
  94 #
  95 # CPU  DURATION                  FUNCTION CALLS
  96 # |     |   |                     |   |   |   |
  97  1)               |  can_send() {
  98  1)               |    dev_queue_xmit() {
  99  1)               |      rt_spin_lock() {
 100  1)   0.894 us    |        __might_sleep();
 101  1)   2.750 us    |      }
 102  1)               |      pfifo_fast_enqueue() {
 103  1)               |        kfree_skb() {
 104  1)               |          __kfree_skb() {
 105  1)               |            skb_release_head_state() {
 106  1)               |              sock_wfree() {
 107  1)               |                sock_def_write_space() {
 108  1)               |                  rt_read_lock() {
 109  1)               |                    __rt_spin_lock() {
 110  1)   0.677 us    |                      __might_sleep();
 111  1)   2.386 us    |                    }
 112  1)   4.150 us    |                  }
 113  1)               |                  rt_read_unlock() {
 114  1)   0.918 us    |                    __rt_spin_unlock();
 115  1)   2.644 us    |                  }
 116  1)   9.375 us    |                }
 117  1) + 10.999 us   |              }
 118  1) + 12.708 us   |            }
 119  1)               |            skb_release_data() {
 120  1)               |              kfree() {
 121  1)               |                _slab_irq_disable() {
 122  1)               |                  rt_spin_lock() {
 123  1)   0.849 us    |                    __might_sleep();
 124  1)   2.588 us    |                  }
 125  1)   4.242 us    |                }
 126  1)   0.864 us    |                __cache_free();
 127  1)   0.888 us    |                rt_spin_unlock();
 128  1)   9.456 us    |              }
 129  1) + 11.185 us   |            }
 130  1)               |            kmem_cache_free() {
 131  1)               |              _slab_irq_disable() {
 132  1)               |                rt_spin_lock() {
 133  1)   0.812 us    |                  __might_sleep();
 134  1)   2.542 us    |                }
 135  1)   4.240 us    |              }
 136  1)   0.813 us    |              __cache_free();
 137  1)   0.894 us    |              rt_spin_unlock();
 138  1)   9.329 us    |            }
 139  1) + 36.444 us   |          }
 140  1) + 38.136 us   |        }
 141  1) + 39.974 us   |      }
 142  1)               |      /* qdisc_enqueue_root = 1 */
 143  1)               |      __qdisc_run() {
 144  1)               |        sch_direct_xmit() {
 145  1)   0.855 us    |          rt_spin_unlock();
 146  1)               |          rt_spin_lock() {
 147  1)   0.827 us    |            __might_sleep();
 148  1)   2.521 us    |          }
 149  1)               |          dev_hard_start_xmit() {
 150  1)               |            sja1000_start_xmit() {
 151  1)   1.646 us    |              kvaser_pci_write_reg();
 152  1)   1.460 us    |              kvaser_pci_write_reg();
 153  1)   1.691 us    |              kvaser_pci_write_reg();
 154  1)   1.450 us    |              kvaser_pci_write_reg();
 155  1)   1.416 us    |              kvaser_pci_write_reg();
 156  1)               |              can_put_echo_skb() {
 157  1)               |                sock_wfree() {
 158  1)               |                  sock_def_write_space() {
 159  1)               |                    rt_read_lock() {
 160  1)               |                      __rt_spin_lock() {
 161  1)   0.939 us    |                        __might_sleep();
 162  1)   2.699 us    |                      }
 163  1)   4.337 us    |                    }
 164  1)               |                    rt_read_unlock() {
 165  1)   0.844 us    |                      __rt_spin_unlock();
 166  1)   2.507 us    |                    }
 167  1)   9.242 us    |                  }
 168  1) + 11.047 us   |                }
 169  1) + 12.791 us   |              }
 170  1)               |              sja1000_write_cmdreg() {
 171  1)               |                rt_spin_lock() {
 172  1)   0.802 us    |                  __might_sleep();
 173  1)   2.532 us    |                }
 174  1)   1.481 us    |                kvaser_pci_write_reg();
 175  1)   2.155 us    |                kvaser_pci_read_reg();
 176  1)   0.843 us    |                rt_spin_unlock();
 177  1) + 11.100 us   |              }
 178  1) + 38.263 us   |            }
 179  1)               |            /* ops->ndo_start_xmit(skb, dev) = 0 */
 180  1) + 41.508 us   |          }
 181  1)               |          /* dev_hard_start_xmit(skb, dev) = 0 */
 182  1)   0.884 us    |          rt_spin_unlock();
 183  1)               |          rt_spin_lock() {
 184  1)   0.817 us    |            __might_sleep();
 185  1)   2.583 us    |          }
 186  1)               |          /* qdisc_len = 9 */
 187  1)               |          /* sch_direct_xmit returns 0 */
 188  1) + 57.502 us   |        }
 189  1) + 59.288 us   |      }
 190  1)   0.877 us    |      rt_spin_unlock();
 191  1)               |      /* __dev_xmit_skb = 1 */
 192  1) ! 111.265 us  |    }
 193  1)               |  /* dev_queue_xmit = 1 */
 194  1)               |  /* net_xmit_errno = -105 */
 195  1)   0.956 us    |    kfree_skb();
 196  1) ! 117.340 us  |  }
 197  1)               |  /* write returned -1 */
 198
 199 ** The trace was generated by kernel v2.6.33.7-rt29-4-g92487e4 with the following patch applied:
 200
 201 diff --git a/net/can/af_can.c b/net/can/af_can.c
 202 index 4d8479d7..c91968d 100644
 203 --- a/net/can/af_can.c
 204 +++ b/net/can/af_can.c
 205 @@ -344,8 +344,11 @@ int can_send(struct sk_buff *skb, int loop)
 206
 207         /* send to netdevice */
 208         err = dev_queue_xmit(skb);
 209 -       if (err > 0)
 210 +       trace_printk("dev_queue_xmit = %d\n", err);
 211 +       if (err > 0) {
 212                 err = net_xmit_errno(err);
 213 +               trace_printk("net_xmit_errno = %d\n", err);
 214 +       }
 215
 216         if (err) {
 217  #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,17)
 218 diff --git a/net/core/dev.c b/net/core/dev.c
 219 index 7a5412e..10ca9b4 100644
 220 --- a/net/core/dev.c
 221 +++ b/net/core/dev.c
 222 @@ -1828,6 +1828,8 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 223                         skb_dst_drop(skb);
 224
 225                 rc = ops->ndo_start_xmit(skb, dev);
 226 +               trace_printk("ops->ndo_start_xmit(skb, dev) = %d\n", rc);
 227 +
 228                 if (rc == NETDEV_TX_OK)
 229                         txq_trans_update(txq);
 230                 /*
 231 @@ -1854,6 +1856,7 @@ gso:
 232                 skb->next = nskb->next;
 233                 nskb->next = NULL;
 234                 rc = ops->ndo_start_xmit(nskb, dev);
 235 +               trace_printk("gso: ops->ndo_start_xmit(skb, dev) = %d\n", rc);
 236                 if (unlikely(rc != NETDEV_TX_OK)) {
 237                         if (rc & ~NETDEV_TX_MASK)
 238                                 goto out_kfree_gso_skb;
 239 @@ -1949,6 +1952,8 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
 240         spin_lock(root_lock);
 241         if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
 242                 kfree_skb(skb);
 243 +               trace_printk("QDISC_STATE_DEACTIVATED\n");
 244 +
 245                 rc = NET_XMIT_DROP;
 246         } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) &&
 247                    !test_and_set_bit(__QDISC_STATE_RUNNING, &q->state)) {
 248 @@ -1966,6 +1971,7 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
 249                 rc = NET_XMIT_SUCCESS;
 250         } else {
 251                 rc = qdisc_enqueue_root(skb, q);
 252 +               trace_printk("qdisc_enqueue_root = %d\n", rc);
 253                 qdisc_run(q);
 254         }
 255         spin_unlock(root_lock);
 256 @@ -2047,6 +2053,7 @@ gso:
 257  #endif
 258         if (q->enqueue) {
 259                 rc = __dev_xmit_skb(skb, q, dev, txq);
 260 +               trace_printk("__dev_xmit_skb = %d\n", rc);
 261                 goto out;
 262         }
 263
 264 @@ -2072,6 +2079,8 @@ gso:
 265
 266                         if (!netif_tx_queue_stopped(txq)) {
 267                                 rc = dev_hard_start_xmit(skb, dev, txq);
 268 +                               trace_printk("dev_hard_start_xmit = %d\n", rc);
 269 +
 270                                 if (dev_xmit_complete(rc)) {
 271                                         HARD_TX_UNLOCK(dev, txq);
 272                                         goto out;
 273 diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
 274 index bf7f50e..aea0833 100644
 275 --- a/net/sched/sch_generic.c
 276 +++ b/net/sched/sch_generic.c
 277 @@ -125,6 +125,7 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 278         HARD_TX_LOCK(dev, txq);
 279         if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq))
 280                 ret = dev_hard_start_xmit(skb, dev, txq);
 281 +       trace_printk("dev_hard_start_xmit(skb, dev) = %d\n", ret);
 282
 283         HARD_TX_UNLOCK(dev, txq);
 284
 285 @@ -133,9 +134,11 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 286         if (dev_xmit_complete(ret)) {
 287                 /* Driver sent out skb successfully or skb was consumed */
 288                 ret = qdisc_qlen(q);
 289 +               trace_printk("qdisc_len = %d\n", ret);
 290         } else if (ret == NETDEV_TX_LOCKED) {
 291                 /* Driver try lock failed */
 292                 ret = handle_dev_cpu_collision(skb, txq, q);
 293 +               trace_printk("handle_dev_cpu_collision = %d\n", ret);
 294         } else {
 295                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 296                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
 297 @@ -143,12 +146,13 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 298                                dev->name, ret, q->q.qlen);
 299
 300                 ret = dev_requeue_skb(skb, q);
 301 +               trace_printk("dev_requeue_skb = %d\n", ret);
 302         }
 303
 304         if (ret && (netif_tx_queue_stopped(txq) ||
 305                     netif_tx_queue_frozen(txq)))
 306                 ret = 0;
 307 -
 308 +       trace_printk("%s returns %d\n", __FUNCTION__, ret);
 309         return ret;
 310  }
 311