diff options
Diffstat (limited to 'Documentation/networking/netif-msg.txt')
| -rw-r--r-- | Documentation/networking/netif-msg.txt | 79 |
1 files changed, 0 insertions, 79 deletions
diff --git a/Documentation/networking/netif-msg.txt b/Documentation/networking/netif-msg.txt deleted file mode 100644 index c967ddb90d0b..000000000000 --- a/Documentation/networking/netif-msg.txt +++ /dev/null @@ -1,79 +0,0 @@ - -________________ -NETIF Msg Level - -The design of the network interface message level setting. - -History - - The design of the debugging message interface was guided and - constrained by backwards compatibility previous practice. It is useful - to understand the history and evolution in order to understand current - practice and relate it to older driver source code. - - From the beginning of Linux, each network device driver has had a local - integer variable that controls the debug message level. The message - level ranged from 0 to 7, and monotonically increased in verbosity. - - The message level was not precisely defined past level 3, but were - always implemented within +-1 of the specified level. Drivers tended - to shed the more verbose level messages as they matured. - 0 Minimal messages, only essential information on fatal errors. - 1 Standard messages, initialization status. No run-time messages - 2 Special media selection messages, generally timer-driver. - 3 Interface starts and stops, including normal status messages - 4 Tx and Rx frame error messages, and abnormal driver operation - 5 Tx packet queue information, interrupt events. - 6 Status on each completed Tx packet and received Rx packets - 7 Initial contents of Tx and Rx packets - - Initially this message level variable was uniquely named in each driver - e.g. "lance_debug", so that a kernel symbolic debugger could locate and - modify the setting. When kernel modules became common, the variables - were consistently renamed to "debug" and allowed to be set as a module - parameter. - - This approach worked well. However there is always a demand for - additional features. Over the years the following emerged as - reasonable and easily implemented enhancements - Using an ioctl() call to modify the level. - Per-interface rather than per-driver message level setting. - More selective control over the type of messages emitted. - - The netif_msg recommendation adds these features with only a minor - complexity and code size increase. - - The recommendation is the following points - Retaining the per-driver integer variable "debug" as a module - parameter with a default level of '1'. - - Adding a per-interface private variable named "msg_enable". The - variable is a bit map rather than a level, and is initialized as - 1 << debug - Or more precisely - debug < 0 ? 0 : 1 << min(sizeof(int)-1, debug) - - Messages should changes from - if (debug > 1) - printk(MSG_DEBUG "%s: ... - to - if (np->msg_enable & NETIF_MSG_LINK) - printk(MSG_DEBUG "%s: ... - - -The set of message levels is named - Old level Name Bit position - 0 NETIF_MSG_DRV 0x0001 - 1 NETIF_MSG_PROBE 0x0002 - 2 NETIF_MSG_LINK 0x0004 - 2 NETIF_MSG_TIMER 0x0004 - 3 NETIF_MSG_IFDOWN 0x0008 - 3 NETIF_MSG_IFUP 0x0008 - 4 NETIF_MSG_RX_ERR 0x0010 - 4 NETIF_MSG_TX_ERR 0x0010 - 5 NETIF_MSG_TX_QUEUED 0x0020 - 5 NETIF_MSG_INTR 0x0020 - 6 NETIF_MSG_TX_DONE 0x0040 - 6 NETIF_MSG_RX_STATUS 0x0040 - 7 NETIF_MSG_PKTDATA 0x0080 - |